import { useEffect, useMemo, useRef, useState } from "react";
import { useMutation } from "@tanstack/react-query";
import type { CompanyPortabilityExportResult } from "@paperclipai/shared";
import { useCompany } from "../context/CompanyContext";
import { useBreadcrumbs } from "../context/BreadcrumbContext";
import { useToast } from "../context/ToastContext";
import { companiesApi } from "../api/companies";
import { Button } from "@/components/ui/button";
import { EmptyState } from "../components/EmptyState";
import { PageSkeleton } from "../components/PageSkeleton";
import { MarkdownBody } from "../components/MarkdownBody";
import { cn } from "../lib/utils";
import { createZipArchive } from "../lib/zip";
import {
  ChevronDown,
  ChevronRight,
  Download,
  FileCode2,
  FileText,
  Folder,
  FolderOpen,
  Package,
  Search,
} from "lucide-react";

// ── Tree types ────────────────────────────────────────────────────────

type FileTreeNode = {
  name: string;
  path: string;
  kind: "dir" | "file";
  children: FileTreeNode[];
};

const TREE_BASE_INDENT = 16;
const TREE_STEP_INDENT = 24;
const TREE_ROW_HEIGHT_CLASS = "min-h-9";

// ── Helpers ───────────────────────────────────────────────────────────

function buildFileTree(files: Record<string, string>): FileTreeNode[] {
  const root: FileTreeNode = { name: "", path: "", kind: "dir", children: [] };

  for (const filePath of Object.keys(files)) {
    const segments = filePath.split("/").filter(Boolean);
    let current = root;
    let currentPath = "";
    for (let i = 0; i < segments.length; i++) {
      const segment = segments[i];
      currentPath = currentPath ? `${currentPath}/${segment}` : segment;
      const isLeaf = i === segments.length - 1;
      let next = current.children.find((c) => c.name === segment);
      if (!next) {
        next = {
          name: segment,
          path: currentPath,
          kind: isLeaf ? "file" : "dir",
          children: [],
        };
        current.children.push(next);
      }
      current = next;
    }
  }

  function sortNode(node: FileTreeNode) {
    node.children.sort((a, b) => {
      // Files before directories so PROJECT.md appears above tasks/
      if (a.kind !== b.kind) return a.kind === "file" ? -1 : 1;
      return a.name.localeCompare(b.name);
    });
    node.children.forEach(sortNode);
  }

  sortNode(root);
  return root.children;
}

function countFiles(nodes: FileTreeNode[]): number {
  let count = 0;
  for (const node of nodes) {
    if (node.kind === "file") count++;
    else count += countFiles(node.children);
  }
  return count;
}

function collectAllPaths(
  nodes: FileTreeNode[],
  type: "file" | "dir" | "all" = "all",
): Set<string> {
  const paths = new Set<string>();
  for (const node of nodes) {
    if (type === "all" || node.kind === type) paths.add(node.path);
    for (const p of collectAllPaths(node.children, type)) paths.add(p);
  }
  return paths;
}

function fileIcon(name: string) {
  if (name.endsWith(".yaml") || name.endsWith(".yml")) return FileCode2;
  return FileText;
}

/** Returns true if the path looks like a task file (e.g. tasks/slug/TASK.md or projects/x/tasks/slug/TASK.md) */
function isTaskPath(filePath: string): boolean {
  return /(?:^|\/)tasks\//.test(filePath);
}

/**
 * Extract the set of agent/project/task slugs that are "checked" based on
 * which file paths are in the checked set.
 *   agents/{slug}/AGENT.md   → agents slug
 *   projects/{slug}/PROJECT.md → projects slug
 *   tasks/{slug}/TASK.md     → tasks slug
 */
function checkedSlugs(checkedFiles: Set<string>): {
  agents: Set<string>;
  projects: Set<string>;
  tasks: Set<string>;
} {
  const agents = new Set<string>();
  const projects = new Set<string>();
  const tasks = new Set<string>();
  for (const p of checkedFiles) {
    const agentMatch = p.match(/^agents\/([^/]+)\//);
    if (agentMatch) agents.add(agentMatch[1]);
    const projectMatch = p.match(/^projects\/([^/]+)\//);
    if (projectMatch) projects.add(projectMatch[1]);
    const taskMatch = p.match(/^tasks\/([^/]+)\//);
    if (taskMatch) tasks.add(taskMatch[1]);
  }
  return { agents, projects, tasks };
}

/**
 * Filter .paperclip.yaml content so it only includes entries whose
 * corresponding files are checked. Works by line-level YAML parsing
 * since the file has a known, simple structure produced by our own
 * renderYamlBlock.
 */
function filterPaperclipYaml(yaml: string, checkedFiles: Set<string>): string {
  const slugs = checkedSlugs(checkedFiles);
  const lines = yaml.split("\n");
  const out: string[] = [];

  // Sections whose entries are slug-keyed and should be filtered
  const filterableSections = new Set(["agents", "projects", "tasks"]);

  let currentSection: string | null = null; // top-level key (e.g. "agents")
  let currentEntry: string | null = null;   // slug under that section
  let includeEntry = true;
  // Collect entries per section so we can omit empty section headers
  let sectionHeaderLine: string | null = null;
  let sectionBuffer: string[] = [];

  function flushSection() {
    if (sectionHeaderLine !== null && sectionBuffer.length > 0) {
      out.push(sectionHeaderLine);
      out.push(...sectionBuffer);
    }
    sectionHeaderLine = null;
    sectionBuffer = [];
  }

  for (const line of lines) {
    // Detect top-level key (no indentation)
    const topMatch = line.match(/^([a-zA-Z_][\w-]*):\s*(.*)$/);
    if (topMatch && !line.startsWith(" ")) {
      // Flush previous section
      flushSection();
      currentEntry = null;
      includeEntry = true;

      const key = topMatch[0].split(":")[0];
      if (filterableSections.has(key)) {
        currentSection = key;
        sectionHeaderLine = line;
        continue;
      } else {
        currentSection = null;
        out.push(line);
        continue;
      }
    }

    // Inside a filterable section
    if (currentSection && filterableSections.has(currentSection)) {
      // 2-space indented key = entry slug (slugs may start with digits/hyphens)
      const entryMatch = line.match(/^  ([\w][\w-]*):\s*(.*)$/);
      if (entryMatch && !line.startsWith("    ")) {
        const slug = entryMatch[1];
        currentEntry = slug;
        const sectionSlugs = slugs[currentSection as keyof typeof slugs];
        includeEntry = sectionSlugs.has(slug);
        if (includeEntry) sectionBuffer.push(line);
        continue;
      }

      // Deeper indented line belongs to current entry
      if (currentEntry !== null) {
        if (includeEntry) sectionBuffer.push(line);
        continue;
      }

      // Shouldn't happen in well-formed output, but pass through
      sectionBuffer.push(line);
      continue;
    }

    // Outside filterable sections — pass through
    out.push(line);
  }

  // Flush last section
  flushSection();

  return out.join("\n");
}

/** Filter tree nodes whose path (or descendant paths) match a search string */
function filterTree(nodes: FileTreeNode[], query: string): FileTreeNode[] {
  if (!query) return nodes;
  const lower = query.toLowerCase();
  return nodes
    .map((node) => {
      if (node.kind === "file") {
        return node.name.toLowerCase().includes(lower) || node.path.toLowerCase().includes(lower)
          ? node
          : null;
      }
      const filteredChildren = filterTree(node.children, query);
      return filteredChildren.length > 0
        ? { ...node, children: filteredChildren }
        : null;
    })
    .filter((n): n is FileTreeNode => n !== null);
}

/** Collect all ancestor dir paths for files that match a filter */
function collectMatchedParentDirs(nodes: FileTreeNode[], query: string): Set<string> {
  const dirs = new Set<string>();
  const lower = query.toLowerCase();

  function walk(node: FileTreeNode, ancestors: string[]) {
    if (node.kind === "file") {
      if (node.name.toLowerCase().includes(lower) || node.path.toLowerCase().includes(lower)) {
        for (const a of ancestors) dirs.add(a);
      }
    } else {
      for (const child of node.children) {
        walk(child, [...ancestors, node.path]);
      }
    }
  }

  for (const node of nodes) walk(node, []);
  return dirs;
}

/** Sort tree: checked files first, then unchecked */
function sortByChecked(nodes: FileTreeNode[], checkedFiles: Set<string>): FileTreeNode[] {
  return nodes.map((node) => {
    if (node.kind === "dir") {
      return { ...node, children: sortByChecked(node.children, checkedFiles) };
    }
    return node;
  }).sort((a, b) => {
    if (a.kind !== b.kind) return a.kind === "file" ? -1 : 1;
    if (a.kind === "file" && b.kind === "file") {
      const aChecked = checkedFiles.has(a.path);
      const bChecked = checkedFiles.has(b.path);
      if (aChecked !== bChecked) return aChecked ? -1 : 1;
    }
    return a.name.localeCompare(b.name);
  });
}

const TASKS_PAGE_SIZE = 10;

/**
 * Paginate children of `tasks/` directories: show up to `limit` entries,
 * but always include children that are checked or match the search query.
 * Returns the paginated tree and the total count of task children.
 */
function paginateTaskNodes(
  nodes: FileTreeNode[],
  limit: number,
  checkedFiles: Set<string>,
  searchQuery: string,
): { nodes: FileTreeNode[]; totalTaskChildren: number; visibleTaskChildren: number } {
  let totalTaskChildren = 0;
  let visibleTaskChildren = 0;

  const result = nodes.map((node) => {
    // Only paginate direct children of "tasks" directories
    if (node.kind === "dir" && node.name === "tasks") {
      totalTaskChildren = node.children.length;

      // Partition children: pinned (checked or search-matched) vs rest
      const pinned: FileTreeNode[] = [];
      const rest: FileTreeNode[] = [];
      const lower = searchQuery.toLowerCase();

      for (const child of node.children) {
        const childFiles = collectAllPaths([child], "file");
        const isChecked = [...childFiles].some((p) => checkedFiles.has(p));
        const isSearchMatch = searchQuery && (
          child.name.toLowerCase().includes(lower) ||
          child.path.toLowerCase().includes(lower) ||
          [...childFiles].some((p) => p.toLowerCase().includes(lower))
        );
        if (isChecked || isSearchMatch) {
          pinned.push(child);
        } else {
          rest.push(child);
        }
      }

      // Show pinned + up to `limit` from rest
      const remaining = Math.max(0, limit - pinned.length);
      const visible = [...pinned, ...rest.slice(0, remaining)];
      visibleTaskChildren = visible.length;

      return { ...node, children: visible };
    }
    return node;
  });

  return { nodes: result, totalTaskChildren, visibleTaskChildren };
}

function downloadZip(
  exported: CompanyPortabilityExportResult,
  selectedFiles: Set<string>,
  effectiveFiles: Record<string, string>,
) {
  const filteredFiles: Record<string, string> = {};
  for (const [path] of Object.entries(exported.files)) {
    if (selectedFiles.has(path)) filteredFiles[path] = effectiveFiles[path] ?? exported.files[path];
  }
  const zipBytes = createZipArchive(filteredFiles, exported.rootPath);
  const zipBuffer = new ArrayBuffer(zipBytes.byteLength);
  new Uint8Array(zipBuffer).set(zipBytes);
  const blob = new Blob([zipBuffer], { type: "application/zip" });
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement("a");
  anchor.href = url;
  anchor.download = `${exported.rootPath}.zip`;
  document.body.appendChild(anchor);
  anchor.click();
  anchor.remove();
  window.setTimeout(() => URL.revokeObjectURL(url), 1000);
}

// ── File tree component ───────────────────────────────────────────────

function ExportFileTree({
  nodes,
  selectedFile,
  expandedDirs,
  checkedFiles,
  onToggleDir,
  onSelectFile,
  onToggleCheck,
  depth = 0,
}: {
  nodes: FileTreeNode[];
  selectedFile: string | null;
  expandedDirs: Set<string>;
  checkedFiles: Set<string>;
  onToggleDir: (path: string) => void;
  onSelectFile: (path: string) => void;
  onToggleCheck: (path: string, kind: "file" | "dir") => void;
  depth?: number;
}) {
  return (
    <div>
      {nodes.map((node) => {
        const expanded = node.kind === "dir" && expandedDirs.has(node.path);
        if (node.kind === "dir") {
          const childFiles = collectAllPaths(node.children, "file");
          const allChecked = [...childFiles].every((p) => checkedFiles.has(p));
          const someChecked = [...childFiles].some((p) => checkedFiles.has(p));
          return (
            <div key={node.path}>
              <div
                className={cn(
                  "group grid w-full grid-cols-[auto_minmax(0,1fr)_2.25rem] items-center gap-x-1 pr-3 text-left text-sm text-muted-foreground hover:bg-accent/30 hover:text-foreground",
                  TREE_ROW_HEIGHT_CLASS,
                )}
                style={{
                  paddingInlineStart: `${TREE_BASE_INDENT + depth * TREE_STEP_INDENT - 8}px`,
                }}
              >
                <label
                  className="flex items-center pl-2"
                >
                  <input
                    type="checkbox"
                    checked={allChecked}
                    ref={(el) => { if (el) el.indeterminate = someChecked && !allChecked; }}
                    onChange={() => onToggleCheck(node.path, "dir")}
                    className="mr-2 accent-foreground"
                  />
                </label>
                <button
                  type="button"
                  className="flex min-w-0 items-center gap-2 py-1 text-left"
                  onClick={() => onToggleDir(node.path)}
                >
                  <span className="flex h-4 w-4 shrink-0 items-center justify-center">
                    {expanded ? (
                      <FolderOpen className="h-3.5 w-3.5" />
                    ) : (
                      <Folder className="h-3.5 w-3.5" />
                    )}
                  </span>
                  <span className="truncate">{node.name}</span>
                </button>
                <button
                  type="button"
                  className="flex h-9 w-9 items-center justify-center self-center rounded-sm text-muted-foreground opacity-70 transition-[background-color,color,opacity] hover:bg-accent hover:text-foreground group-hover:opacity-100"
                  onClick={() => onToggleDir(node.path)}
                >
                  {expanded ? (
                    <ChevronDown className="h-3.5 w-3.5" />
                  ) : (
                    <ChevronRight className="h-3.5 w-3.5" />
                  )}
                </button>
              </div>
              {expanded && (
                <ExportFileTree
                  nodes={node.children}
                  selectedFile={selectedFile}
                  expandedDirs={expandedDirs}
                  checkedFiles={checkedFiles}
                  onToggleDir={onToggleDir}
                  onSelectFile={onSelectFile}
                  onToggleCheck={onToggleCheck}
                  depth={depth + 1}
                />
              )}
            </div>
          );
        }

        const FileIcon = fileIcon(node.name);
        const checked = checkedFiles.has(node.path);
        return (
          <div
            key={node.path}
            className={cn(
              "flex w-full items-center gap-1 pr-3 text-left text-sm text-muted-foreground hover:bg-accent/30 hover:text-foreground cursor-pointer",
              TREE_ROW_HEIGHT_CLASS,
              node.path === selectedFile && "text-foreground bg-accent/20",
            )}
            style={{
              paddingInlineStart: `${TREE_BASE_INDENT + depth * TREE_STEP_INDENT - 8}px`,
            }}
          >
            <label className="flex items-center pl-2">
              <input
                type="checkbox"
                checked={checked}
                onChange={() => onToggleCheck(node.path, "file")}
                className="mr-2 accent-foreground"
              />
            </label>
            <button
              type="button"
              className="flex min-w-0 flex-1 items-center gap-2 py-1 text-left"
              onClick={() => onSelectFile(node.path)}
            >
              <span className="flex h-4 w-4 shrink-0 items-center justify-center">
                <FileIcon className="h-3.5 w-3.5" />
              </span>
              <span className="truncate">{node.name}</span>
            </button>
          </div>
        );
      })}
    </div>
  );
}

// ── Frontmatter helpers ───────────────────────────────────────────────

type FrontmatterData = Record<string, string | string[]>;

function parseFrontmatter(content: string): { data: FrontmatterData; body: string } | null {
  const match = content.match(/^---\r?\n([\s\S]*?)\r?\n---\r?\n?([\s\S]*)$/);
  if (!match) return null;

  const data: FrontmatterData = {};
  const rawYaml = match[1];
  const body = match[2];

  let currentKey: string | null = null;
  let currentList: string[] | null = null;

  for (const line of rawYaml.split("\n")) {
    const trimmed = line.trim();
    if (!trimmed || trimmed.startsWith("#")) continue;

    // List item under current key
    if (trimmed.startsWith("- ") && currentKey) {
      if (!currentList) currentList = [];
      currentList.push(trimmed.slice(2).trim().replace(/^["']|["']$/g, ""));
      continue;
    }

    // Flush previous list
    if (currentKey && currentList) {
      data[currentKey] = currentList;
      currentList = null;
      currentKey = null;
    }

    const kvMatch = trimmed.match(/^([a-zA-Z_][\w-]*)\s*:\s*(.*)$/);
    if (kvMatch) {
      const key = kvMatch[1];
      const val = kvMatch[2].trim().replace(/^["']|["']$/g, "");
      // Skip null values
      if (val === "null") {
        currentKey = null;
        continue;
      }
      if (val) {
        data[key] = val;
        currentKey = null;
      } else {
        currentKey = key;
      }
    }
  }

  // Flush trailing list
  if (currentKey && currentList) {
    data[currentKey] = currentList;
  }

  return Object.keys(data).length > 0 ? { data, body } : null;
}

const FRONTMATTER_FIELD_LABELS: Record<string, string> = {
  name: "Name",
  title: "Title",
  kind: "Kind",
  reportsTo: "Reports to",
  skills: "Skills",
  status: "Status",
  description: "Description",
  priority: "Priority",
  assignee: "Assignee",
  project: "Project",
  targetDate: "Target date",
};

function FrontmatterCard({
  data,
  onSkillClick,
}: {
  data: FrontmatterData;
  onSkillClick?: (skill: string) => void;
}) {
  return (
    <div className="rounded-md border border-border bg-accent/20 px-4 py-3 mb-4">
      <dl className="grid grid-cols-[auto_minmax(0,1fr)] gap-x-4 gap-y-1.5 text-sm">
        {Object.entries(data).map(([key, value]) => (
          <div key={key} className="contents">
            <dt className="text-muted-foreground whitespace-nowrap py-0.5">
              {FRONTMATTER_FIELD_LABELS[key] ?? key}
            </dt>
            <dd className="py-0.5">
              {Array.isArray(value) ? (
                <div className="flex flex-wrap gap-1.5">
                  {value.map((item) => (
                    <button
                      key={item}
                      type="button"
                      className={cn(
                        "inline-flex items-center rounded-md border border-border bg-background px-2 py-0.5 text-xs",
                        key === "skills" && onSkillClick && "cursor-pointer hover:bg-accent/50 hover:border-foreground/30 transition-colors",
                      )}
                      onClick={() => key === "skills" && onSkillClick?.(item)}
                    >
                      {item}
                    </button>
                  ))}
                </div>
              ) : (
                <span>{value}</span>
              )}
            </dd>
          </div>
        ))}
      </dl>
    </div>
  );
}

// ── Preview pane ──────────────────────────────────────────────────────

function ExportPreviewPane({
  selectedFile,
  content,
  onSkillClick,
}: {
  selectedFile: string | null;
  content: string | null;
  onSkillClick?: (skill: string) => void;
}) {
  if (!selectedFile || content === null) {
    return (
      <EmptyState icon={Package} message="Select a file to preview its contents." />
    );
  }

  const isMarkdown = selectedFile.endsWith(".md");
  const parsed = isMarkdown ? parseFrontmatter(content) : null;

  return (
    <div className="min-w-0">
      <div className="border-b border-border px-5 py-3">
        <div className="truncate font-mono text-sm">{selectedFile}</div>
      </div>
      <div className="min-h-[560px] px-5 py-5">
        {parsed ? (
          <>
            <FrontmatterCard data={parsed.data} onSkillClick={onSkillClick} />
            {parsed.body.trim() && <MarkdownBody>{parsed.body}</MarkdownBody>}
          </>
        ) : isMarkdown ? (
          <MarkdownBody>{content}</MarkdownBody>
        ) : (
          <pre className="overflow-x-auto whitespace-pre-wrap break-words border-0 bg-transparent p-0 font-mono text-sm text-foreground">
            <code>{content}</code>
          </pre>
        )}
      </div>
    </div>
  );
}

// ── Main page ─────────────────────────────────────────────────────────

export function CompanyExport() {
  const { selectedCompanyId, selectedCompany } = useCompany();
  const { setBreadcrumbs } = useBreadcrumbs();
  const { pushToast } = useToast();

  const [exportData, setExportData] = useState<CompanyPortabilityExportResult | null>(null);
  const [selectedFile, setSelectedFile] = useState<string | null>(null);
  const [expandedDirs, setExpandedDirs] = useState<Set<string>>(new Set());
  const [checkedFiles, setCheckedFiles] = useState<Set<string>>(new Set());
  const [treeSearch, setTreeSearch] = useState("");
  const [taskLimit, setTaskLimit] = useState(TASKS_PAGE_SIZE);
  const savedExpandedRef = useRef<Set<string> | null>(null);

  useEffect(() => {
    setBreadcrumbs([
      { label: "Org Chart", href: "/org" },
      { label: "Export" },
    ]);
  }, [setBreadcrumbs]);

  // Load export data on mount
  const exportMutation = useMutation({
    mutationFn: () =>
      companiesApi.exportBundle(selectedCompanyId!, {
        include: { company: true, agents: true, projects: true, issues: true },
      }),
    onSuccess: (result) => {
      setExportData(result);
      // Check all files EXCEPT tasks by default
      const checked = new Set<string>();
      for (const filePath of Object.keys(result.files)) {
        if (!isTaskPath(filePath)) checked.add(filePath);
      }
      setCheckedFiles(checked);
      // Expand top-level dirs
      const tree = buildFileTree(result.files);
      const topDirs = new Set<string>();
      for (const node of tree) {
        if (node.kind === "dir") topDirs.add(node.path);
      }
      setExpandedDirs(topDirs);
      // Select first file
      const firstFile = Object.keys(result.files)[0];
      if (firstFile) setSelectedFile(firstFile);
    },
    onError: (err) => {
      pushToast({
        tone: "error",
        title: "Export failed",
        body: err instanceof Error ? err.message : "Failed to load export data.",
      });
    },
  });

  useEffect(() => {
    if (selectedCompanyId && !exportData && !exportMutation.isPending) {
      exportMutation.mutate();
    }
    // Only run on mount
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [selectedCompanyId]);

  const tree = useMemo(
    () => (exportData ? buildFileTree(exportData.files) : []),
    [exportData],
  );

  const { displayTree, totalTaskChildren, visibleTaskChildren } = useMemo(() => {
    let result = tree;
    if (treeSearch) result = filterTree(result, treeSearch);
    result = sortByChecked(result, checkedFiles);
    const paginated = paginateTaskNodes(result, taskLimit, checkedFiles, treeSearch);
    return {
      displayTree: paginated.nodes,
      totalTaskChildren: paginated.totalTaskChildren,
      visibleTaskChildren: paginated.visibleTaskChildren,
    };
  }, [tree, treeSearch, checkedFiles, taskLimit]);

  // Recompute .paperclip.yaml content whenever checked files change so
  // the preview & download always reflect the current selection.
  const effectiveFiles = useMemo(() => {
    if (!exportData) return {} as Record<string, string>;
    const yamlPath = exportData.paperclipExtensionPath;
    if (!yamlPath || !exportData.files[yamlPath]) return exportData.files;
    const filtered = { ...exportData.files };
    filtered[yamlPath] = filterPaperclipYaml(exportData.files[yamlPath], checkedFiles);
    return filtered;
  }, [exportData, checkedFiles]);

  const totalFiles = useMemo(() => countFiles(tree), [tree]);
  const selectedCount = checkedFiles.size;

  // Filter out terminated agent messages — they don't need to be shown
  const warnings = useMemo(() => {
    if (!exportData) return [] as string[];
    return exportData.warnings.filter((w) => !/terminated agent/i.test(w));
  }, [exportData]);

  function handleToggleDir(path: string) {
    setExpandedDirs((prev) => {
      const next = new Set(prev);
      if (next.has(path)) next.delete(path);
      else next.add(path);
      return next;
    });
  }

  function handleToggleCheck(path: string, kind: "file" | "dir") {
    if (!exportData) return;
    setCheckedFiles((prev) => {
      const next = new Set(prev);
      if (kind === "file") {
        if (next.has(path)) next.delete(path);
        else next.add(path);
      } else {
        // Find all child file paths under this dir
        const dirTree = buildFileTree(exportData.files);
        const findNode = (nodes: FileTreeNode[], target: string): FileTreeNode | null => {
          for (const n of nodes) {
            if (n.path === target) return n;
            const found = findNode(n.children, target);
            if (found) return found;
          }
          return null;
        };
        const dirNode = findNode(dirTree, path);
        if (dirNode) {
          const childFiles = collectAllPaths(dirNode.children, "file");
          // Add the dir's own file children
          for (const child of dirNode.children) {
            if (child.kind === "file") childFiles.add(child.path);
          }
          const allChecked = [...childFiles].every((p) => next.has(p));
          for (const f of childFiles) {
            if (allChecked) next.delete(f);
            else next.add(f);
          }
        }
      }
      return next;
    });
  }

  function handleSearchChange(query: string) {
    const wasSearching = treeSearch.length > 0;
    const isSearching = query.length > 0;

    if (isSearching && !wasSearching) {
      // Save current expansion state before search
      savedExpandedRef.current = new Set(expandedDirs);
    }

    setTreeSearch(query);

    if (isSearching) {
      // Expand all parent dirs of matched files
      const matchedParents = collectMatchedParentDirs(tree, query);
      setExpandedDirs((prev) => {
        const next = new Set(prev);
        for (const d of matchedParents) next.add(d);
        return next;
      });
    } else if (wasSearching) {
      // Restore pre-search expansion state
      if (savedExpandedRef.current) {
        setExpandedDirs(savedExpandedRef.current);
        savedExpandedRef.current = null;
      }
    }
  }

  function handleSkillClick(skillSlug: string) {
    if (!exportData) return;
    // Find the SKILL.md file for this skill slug
    const skillPath = `skills/${skillSlug}/SKILL.md`;
    if (!(skillPath in exportData.files)) return;
    // Select the file and expand parent dirs
    setSelectedFile(skillPath);
    setExpandedDirs((prev) => {
      const next = new Set(prev);
      next.add("skills");
      next.add(`skills/${skillSlug}`);
      return next;
    });
  }

  function handleDownload() {
    if (!exportData) return;
    downloadZip(exportData, checkedFiles, effectiveFiles);
    pushToast({
      tone: "success",
      title: "Export downloaded",
      body: `${selectedCount} file${selectedCount === 1 ? "" : "s"} exported as ${exportData.rootPath}.zip`,
    });
  }

  if (!selectedCompanyId) {
    return <EmptyState icon={Package} message="Select a company to export." />;
  }

  if (exportMutation.isPending && !exportData) {
    return <PageSkeleton variant="detail" />;
  }

  if (!exportData) {
    return <EmptyState icon={Package} message="Loading export data..." />;
  }

  const previewContent = selectedFile ? (effectiveFiles[selectedFile] ?? null) : null;

  return (
    <div>
      {/* Sticky top action bar */}
      <div className="sticky top-0 z-10 border-b border-border bg-background px-5 py-3">
        <div className="flex flex-wrap items-center justify-between gap-3">
          <div className="flex items-center gap-4 text-sm">
            <span className="font-medium">
              {selectedCompany?.name ?? "Company"} export
            </span>
            <span className="text-muted-foreground">
              {selectedCount} / {totalFiles} file{totalFiles === 1 ? "" : "s"} selected
            </span>
            {warnings.length > 0 && (
              <span className="text-amber-500">
                {warnings.length} warning{warnings.length === 1 ? "" : "s"}
              </span>
            )}
          </div>
          <Button
            size="sm"
            onClick={handleDownload}
            disabled={selectedCount === 0}
          >
            <Download className="mr-1.5 h-3.5 w-3.5" />
            Export {selectedCount} file{selectedCount === 1 ? "" : "s"}
          </Button>
        </div>
      </div>

      {/* Warnings */}
      {warnings.length > 0 && (
        <div className="mx-5 mt-3 rounded-md border border-amber-500/30 bg-amber-500/5 px-4 py-3">
          {warnings.map((w) => (
            <div key={w} className="text-xs text-amber-500">{w}</div>
          ))}
        </div>
      )}

      {/* Two-column layout */}
      <div className="grid h-[calc(100vh-12rem)] gap-0 xl:grid-cols-[19rem_minmax(0,1fr)]">
        <aside className="flex flex-col border-r border-border overflow-hidden">
          <div className="border-b border-border px-4 py-3 shrink-0">
            <h2 className="text-base font-semibold">Package files</h2>
          </div>
          <div className="border-b border-border px-3 py-2 shrink-0">
            <div className="flex items-center gap-2 rounded-md border border-border px-2 py-1">
              <Search className="h-3.5 w-3.5 text-muted-foreground shrink-0" />
              <input
                type="text"
                value={treeSearch}
                onChange={(e) => handleSearchChange(e.target.value)}
                placeholder="Search files..."
                className="w-full bg-transparent text-sm outline-none placeholder:text-muted-foreground"
              />
            </div>
          </div>
          <div className="flex-1 overflow-y-auto">
            <ExportFileTree
              nodes={displayTree}
              selectedFile={selectedFile}
              expandedDirs={expandedDirs}
              checkedFiles={checkedFiles}
              onToggleDir={handleToggleDir}
              onSelectFile={setSelectedFile}
              onToggleCheck={handleToggleCheck}
            />
            {totalTaskChildren > visibleTaskChildren && !treeSearch && (
              <div className="px-4 py-2">
                <button
                  type="button"
                  onClick={() => setTaskLimit((prev) => prev + TASKS_PAGE_SIZE)}
                  className="w-full rounded-md border border-border px-3 py-1.5 text-xs text-muted-foreground hover:bg-accent/30 hover:text-foreground transition-colors"
                >
                  Show more issues ({visibleTaskChildren} of {totalTaskChildren})
                </button>
              </div>
            )}
          </div>
        </aside>
        <div className="min-w-0 overflow-y-auto pl-6">
          <ExportPreviewPane selectedFile={selectedFile} content={previewContent} onSkillClick={handleSkillClick} />
        </div>
      </div>
    </div>
  );
}