package handlers

import (
	"context"
	"encoding/json"
	"log"
	"net/http"
	"strings"
	"unicode"

	"git.georgsen.dk/hwlab/internal/netbox"
)

// SearchNetBoxClient is the narrow interface the search handler needs.
type SearchNetBoxClient interface {
	ListDevices(ctx context.Context, limit int) ([]netbox.Device, error)
}

// SearchAIClient is the narrow interface for NL→filter translation.
type SearchAIClient interface {
	TextComplete(ctx context.Context, prompt string) (string, error)
}

// nlFilter holds the parsed output from the LLM (T-07-06: only known fields accepted).
type nlFilter struct {
	CatalogStatus string `json:"catalog_status"`
	NameContains  string `json:"name_contains"`
	Tag           string `json:"tag"`
}

// SearchHandler handles GET /api/search?q=...
type SearchHandler struct {
	nbClient SearchNetBoxClient
	tier1    SearchAIClient
}

// NewSearchHandler creates a SearchHandler.
func NewSearchHandler(nb SearchNetBoxClient, tier1 SearchAIClient) *SearchHandler {
	return &SearchHandler{nbClient: nb, tier1: tier1}
}

// SearchDevices handles GET /api/search?q=<natural language query>
// It translates the query to NetBox filter params via Tier 1 LLM, then fetches
// and filters devices accordingly.
func (h *SearchHandler) SearchDevices(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	q := r.URL.Query().Get("q")
	if strings.TrimSpace(q) == "" {
		w.WriteHeader(http.StatusBadRequest)
		_ = json.NewEncoder(w).Encode(map[string]string{"error": "q parameter required"})
		return
	}

	// Sanitize: strip non-printable chars, truncate to 200 chars (T-07-05).
	q = sanitizeQuery(q)

	// Translate NL query to structured filter via Tier 1 LLM.
	filter := h.parseFilter(r.Context(), q)

	// Fetch up to 200 devices from NetBox.
	devices, err := h.nbClient.ListDevices(r.Context(), 200)
	if err != nil {
		w.WriteHeader(http.StatusBadGateway)
		_ = json.NewEncoder(w).Encode(map[string]string{"error": "netbox unavailable: " + err.Error()})
		return
	}

	// Apply filters in-memory and serialize.
	results := make([]map[string]interface{}, 0)
	for _, d := range devices {
		if !matchesFilter(d, filter) {
			continue
		}
		results = append(results, deviceToSearchResponse(d))
	}

	_ = json.NewEncoder(w).Encode(results)
}

// parseFilter calls the LLM and parses its JSON output into an nlFilter.
// On any failure, falls back to a name substring match on the raw query.
func (h *SearchHandler) parseFilter(ctx context.Context, q string) nlFilter {
	resp, err := h.tier1.TextComplete(ctx, nlFilterPrompt(q))
	if err != nil {
		log.Printf("search: LLM TextComplete error: %v — falling back to substring match", err)
		return nlFilter{NameContains: q}
	}

	// Extract JSON from response (LLM may wrap JSON in markdown code fences).
	jsonStr := extractJSON(resp)

	var f nlFilter
	if err := json.Unmarshal([]byte(jsonStr), &f); err != nil {
		log.Printf("search: LLM JSON parse failed: %v — falling back to substring match (raw: %.200s)", err, resp)
		return nlFilter{NameContains: q}
	}

	if f.Tag != "" {
		log.Printf("search: tag filter %q not implemented for MVP — ignoring", f.Tag)
		f.Tag = ""
	}

	return f
}

// matchesFilter returns true if device d satisfies all active filter criteria.
func matchesFilter(d netbox.Device, f nlFilter) bool {
	// catalog_status: exact match (case-insensitive) when set (T-07-06).
	if f.CatalogStatus != "" {
		if !strings.EqualFold(d.CustomFields.CatalogStatus, f.CatalogStatus) {
			return false
		}
	}
	// name_contains: case-insensitive substring match when set.
	if f.NameContains != "" {
		if !strings.Contains(strings.ToLower(d.Name), strings.ToLower(f.NameContains)) {
			return false
		}
	}
	return true
}

// deviceToSearchResponse converts a netbox.Device to the InventoryItem JSON shape.
func deviceToSearchResponse(d netbox.Device) map[string]interface{} {
	cf := d.CustomFields
	urls := cf.PhotoURLs
	if urls == nil {
		urls = []string{}
	}
	var assetTag interface{} = nil
	if d.AssetTag != "" {
		assetTag = d.AssetTag
	}
	return map[string]interface{}{
		"id":               d.ID,
		"name":             d.Name,
		"asset_tag":        assetTag,
		"hw_id":            nilIfEmpty(cf.HWID),
		"catalog_status":   nilIfEmpty(cf.CatalogStatus),
		"product_url":      nilIfEmpty(cf.ProductURL),
		"firmware_version": nilIfEmpty(cf.FirmwareVersion),
		"test_date":        nilIfEmpty(cf.TestDate),
		"test_data":        nilIfEmpty(cf.TestData),
		"ai_notes":         nilIfEmpty(cf.AINotes),
		"photo_urls":       urls,
	}
}

func nilIfEmpty(s string) interface{} {
	if s == "" {
		return nil
	}
	return s
}

// nlFilterPrompt builds the LLM extraction prompt for a given user query.
func nlFilterPrompt(q string) string {
	return `Extract NetBox filter parameters from this inventory search query. Return JSON only: {"catalog_status": "...", "name_contains": "...", "tag": "..."}. All fields optional. Use empty string for fields that don't apply. Valid catalog_status values: draft, indexed, needs_research, researched, complete, available. Query: ` + q
}

// sanitizeQuery strips non-printable characters and truncates to 200 chars.
func sanitizeQuery(q string) string {
	var sb strings.Builder
	for _, r := range q {
		if unicode.IsPrint(r) {
			sb.WriteRune(r)
		}
	}
	result := sb.String()
	runes := []rune(result)
	if len(runes) > 200 {
		result = string(runes[:200])
	}
	return strings.TrimSpace(result)
}

// extractJSON attempts to extract a JSON object from a string that may contain
// markdown code fences or surrounding text.
func extractJSON(s string) string {
	start := strings.Index(s, "{")
	end := strings.LastIndex(s, "}")
	if start >= 0 && end > start {
		return s[start : end+1]
	}
	return s
}