package seating

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
)

// Blueprint is a venue-level saved table layout configuration.
type Blueprint struct {
	ID           int                    `json:"id"`
	Name         string                 `json:"name"`
	TableConfigs []BlueprintTableConfig `json:"table_configs"`
}

// BlueprintTableConfig is a single table spec within a blueprint.
type BlueprintTableConfig struct {
	Name      string `json:"name"`
	SeatCount int    `json:"seat_count"`
}

// BlueprintService provides CRUD operations for table blueprints.
type BlueprintService struct {
	db *sql.DB
}

// NewBlueprintService creates a new BlueprintService.
func NewBlueprintService(db *sql.DB) *BlueprintService {
	return &BlueprintService{db: db}
}

// CreateBlueprint creates a new blueprint.
func (s *BlueprintService) CreateBlueprint(ctx context.Context, name string, configs []BlueprintTableConfig) (*Blueprint, error) {
	if name == "" {
		return nil, fmt.Errorf("blueprint name is required")
	}
	if len(configs) == 0 {
		return nil, fmt.Errorf("at least one table config is required")
	}
	for i, c := range configs {
		if c.SeatCount < 6 || c.SeatCount > 10 {
			return nil, fmt.Errorf("table config %d: seat count must be between 6 and 10", i+1)
		}
		if c.Name == "" {
			return nil, fmt.Errorf("table config %d: name is required", i+1)
		}
	}

	configsJSON, err := json.Marshal(configs)
	if err != nil {
		return nil, fmt.Errorf("marshal configs: %w", err)
	}

	result, err := s.db.ExecContext(ctx,
		`INSERT INTO table_blueprints (name, table_configs) VALUES (?, ?)`,
		name, string(configsJSON),
	)
	if err != nil {
		return nil, fmt.Errorf("create blueprint: %w", err)
	}

	id, _ := result.LastInsertId()
	return &Blueprint{
		ID:           int(id),
		Name:         name,
		TableConfigs: configs,
	}, nil
}

// GetBlueprint returns a blueprint by ID.
func (s *BlueprintService) GetBlueprint(ctx context.Context, id int) (*Blueprint, error) {
	var bp Blueprint
	var configsJSON string
	err := s.db.QueryRowContext(ctx,
		`SELECT id, name, table_configs FROM table_blueprints WHERE id = ?`, id,
	).Scan(&bp.ID, &bp.Name, &configsJSON)
	if err == sql.ErrNoRows {
		return nil, fmt.Errorf("blueprint not found")
	}
	if err != nil {
		return nil, fmt.Errorf("get blueprint: %w", err)
	}
	if err := json.Unmarshal([]byte(configsJSON), &bp.TableConfigs); err != nil {
		return nil, fmt.Errorf("unmarshal configs: %w", err)
	}
	return &bp, nil
}

// ListBlueprints returns all blueprints.
func (s *BlueprintService) ListBlueprints(ctx context.Context) ([]Blueprint, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT id, name, table_configs FROM table_blueprints ORDER BY name`,
	)
	if err != nil {
		return nil, fmt.Errorf("list blueprints: %w", err)
	}
	defer rows.Close()

	var blueprints []Blueprint
	for rows.Next() {
		var bp Blueprint
		var configsJSON string
		if err := rows.Scan(&bp.ID, &bp.Name, &configsJSON); err != nil {
			return nil, fmt.Errorf("scan blueprint: %w", err)
		}
		if err := json.Unmarshal([]byte(configsJSON), &bp.TableConfigs); err != nil {
			return nil, fmt.Errorf("unmarshal configs: %w", err)
		}
		blueprints = append(blueprints, bp)
	}
	return blueprints, rows.Err()
}

// UpdateBlueprint updates a blueprint.
func (s *BlueprintService) UpdateBlueprint(ctx context.Context, bp Blueprint) error {
	if bp.Name == "" {
		return fmt.Errorf("blueprint name is required")
	}
	for i, c := range bp.TableConfigs {
		if c.SeatCount < 6 || c.SeatCount > 10 {
			return fmt.Errorf("table config %d: seat count must be between 6 and 10", i+1)
		}
		if c.Name == "" {
			return fmt.Errorf("table config %d: name is required", i+1)
		}
	}

	configsJSON, err := json.Marshal(bp.TableConfigs)
	if err != nil {
		return fmt.Errorf("marshal configs: %w", err)
	}

	result, err := s.db.ExecContext(ctx,
		`UPDATE table_blueprints SET name = ?, table_configs = ?, updated_at = unixepoch()
		 WHERE id = ?`,
		bp.Name, string(configsJSON), bp.ID,
	)
	if err != nil {
		return fmt.Errorf("update blueprint: %w", err)
	}
	n, _ := result.RowsAffected()
	if n == 0 {
		return fmt.Errorf("blueprint not found")
	}
	return nil
}

// DeleteBlueprint deletes a blueprint.
func (s *BlueprintService) DeleteBlueprint(ctx context.Context, id int) error {
	result, err := s.db.ExecContext(ctx,
		`DELETE FROM table_blueprints WHERE id = ?`, id,
	)
	if err != nil {
		return fmt.Errorf("delete blueprint: %w", err)
	}
	n, _ := result.RowsAffected()
	if n == 0 {
		return fmt.Errorf("blueprint not found")
	}
	return nil
}

// SaveBlueprintFromTournament creates a blueprint from the current tables in a tournament.
func (s *BlueprintService) SaveBlueprintFromTournament(ctx context.Context, db *sql.DB, tournamentID, name string) (*Blueprint, error) {
	if name == "" {
		return nil, fmt.Errorf("blueprint name is required")
	}

	rows, err := db.QueryContext(ctx,
		`SELECT name, seat_count FROM tables
		 WHERE tournament_id = ? AND is_active = 1
		 ORDER BY name`,
		tournamentID,
	)
	if err != nil {
		return nil, fmt.Errorf("get tournament tables: %w", err)
	}
	defer rows.Close()

	var configs []BlueprintTableConfig
	for rows.Next() {
		var c BlueprintTableConfig
		if err := rows.Scan(&c.Name, &c.SeatCount); err != nil {
			return nil, fmt.Errorf("scan table: %w", err)
		}
		configs = append(configs, c)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	if len(configs) == 0 {
		return nil, fmt.Errorf("no active tables in tournament")
	}

	return s.CreateBlueprint(ctx, name, configs)
}

// CreateTablesFromBlueprint creates tables in a tournament from a blueprint.
func (s *BlueprintService) CreateTablesFromBlueprint(ctx context.Context, db *sql.DB, tournamentID string, blueprintID int) ([]Table, error) {
	bp, err := s.GetBlueprint(ctx, blueprintID)
	if err != nil {
		return nil, err
	}

	var tables []Table
	for _, cfg := range bp.TableConfigs {
		result, err := db.ExecContext(ctx,
			`INSERT INTO tables (tournament_id, name, seat_count, is_active)
			 VALUES (?, ?, ?, 1)`,
			tournamentID, cfg.Name, cfg.SeatCount,
		)
		if err != nil {
			return nil, fmt.Errorf("create table from blueprint: %w", err)
		}
		id, _ := result.LastInsertId()
		tables = append(tables, Table{
			ID:           int(id),
			TournamentID: tournamentID,
			Name:         cfg.Name,
			SeatCount:    cfg.SeatCount,
			IsActive:     true,
		})
	}
	return tables, nil
}