package ingredient

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"

	"github.com/food-ai/backend/internal/locale"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

// Repository handles persistence for ingredient_mappings and their translations.
type Repository struct {
	pool *pgxpool.Pool
}

// NewRepository creates a new Repository.
func NewRepository(pool *pgxpool.Pool) *Repository {
	return &Repository{pool: pool}
}

// Upsert inserts or updates an ingredient mapping (English canonical content).
// Conflict is resolved on spoonacular_id when set.
func (r *Repository) Upsert(ctx context.Context, m *IngredientMapping) (*IngredientMapping, error) {
	query := `
		INSERT INTO ingredient_mappings (
			canonical_name, spoonacular_id, aliases,
			category, default_unit,
			calories_per_100g, protein_per_100g, fat_per_100g, carbs_per_100g, fiber_per_100g,
			storage_days
		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
		ON CONFLICT (spoonacular_id) DO UPDATE SET
			canonical_name    = EXCLUDED.canonical_name,
			aliases           = EXCLUDED.aliases,
			category          = EXCLUDED.category,
			default_unit      = EXCLUDED.default_unit,
			calories_per_100g = EXCLUDED.calories_per_100g,
			protein_per_100g  = EXCLUDED.protein_per_100g,
			fat_per_100g      = EXCLUDED.fat_per_100g,
			carbs_per_100g    = EXCLUDED.carbs_per_100g,
			fiber_per_100g    = EXCLUDED.fiber_per_100g,
			storage_days      = EXCLUDED.storage_days,
			updated_at        = now()
		RETURNING id, canonical_name, spoonacular_id, aliases,
			category, default_unit,
			calories_per_100g, protein_per_100g, fat_per_100g, carbs_per_100g, fiber_per_100g,
			storage_days, created_at, updated_at`

	row := r.pool.QueryRow(ctx, query,
		m.CanonicalName, m.SpoonacularID, m.Aliases,
		m.Category, m.DefaultUnit,
		m.CaloriesPer100g, m.ProteinPer100g, m.FatPer100g, m.CarbsPer100g, m.FiberPer100g,
		m.StorageDays,
	)
	return scanMapping(row)
}

// GetBySpoonacularID returns an ingredient mapping by Spoonacular ID.
// CanonicalName is resolved for the language stored in ctx.
// Returns nil, nil if not found.
func (r *Repository) GetBySpoonacularID(ctx context.Context, id int) (*IngredientMapping, error) {
	lang := locale.FromContext(ctx)
	query := `
		SELECT im.id,
			COALESCE(it.name, im.canonical_name) AS canonical_name,
			im.spoonacular_id, im.aliases,
			im.category, im.default_unit,
			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
			im.storage_days, im.created_at, im.updated_at
		FROM ingredient_mappings im
		LEFT JOIN ingredient_translations it ON it.ingredient_id = im.id AND it.lang = $2
		WHERE im.spoonacular_id = $1`

	row := r.pool.QueryRow(ctx, query, id, lang)
	m, err := scanMapping(row)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	return m, err
}

// GetByID returns an ingredient mapping by UUID.
// CanonicalName is resolved for the language stored in ctx.
// Returns nil, nil if not found.
func (r *Repository) GetByID(ctx context.Context, id string) (*IngredientMapping, error) {
	lang := locale.FromContext(ctx)
	query := `
		SELECT im.id,
			COALESCE(it.name, im.canonical_name) AS canonical_name,
			im.spoonacular_id, im.aliases,
			im.category, im.default_unit,
			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
			im.storage_days, im.created_at, im.updated_at
		FROM ingredient_mappings im
		LEFT JOIN ingredient_translations it ON it.ingredient_id = im.id AND it.lang = $2
		WHERE im.id = $1`

	row := r.pool.QueryRow(ctx, query, id, lang)
	m, err := scanMapping(row)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	return m, err
}

// FuzzyMatch finds the single best matching ingredient mapping for a given name.
// Searches both English and translated names for the language in ctx.
// Returns nil, nil when no match is found.
func (r *Repository) FuzzyMatch(ctx context.Context, name string) (*IngredientMapping, error) {
	results, err := r.Search(ctx, name, 1)
	if err != nil {
		return nil, err
	}
	if len(results) == 0 {
		return nil, nil
	}
	return results[0], nil
}

// Search finds ingredient mappings matching the query string.
// Searches English aliases/name and the translated name for the language in ctx.
// Uses a three-level strategy: exact aliases match, ILIKE, and pg_trgm similarity.
func (r *Repository) Search(ctx context.Context, query string, limit int) ([]*IngredientMapping, error) {
	if limit <= 0 {
		limit = 10
	}
	lang := locale.FromContext(ctx)
	q := `
		SELECT im.id,
			COALESCE(it.name, im.canonical_name) AS canonical_name,
			im.spoonacular_id, im.aliases,
			im.category, im.default_unit,
			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
			im.storage_days, im.created_at, im.updated_at
		FROM ingredient_mappings im
		LEFT JOIN ingredient_translations it ON it.ingredient_id = im.id AND it.lang = $3
		WHERE im.aliases    @> to_jsonb(lower($1)::text)
		   OR it.aliases    @> to_jsonb(lower($1)::text)
		   OR im.canonical_name ILIKE '%' || $1 || '%'
		   OR it.name       ILIKE '%' || $1 || '%'
		   OR similarity(COALESCE(it.name, im.canonical_name), $1) > 0.3
		ORDER BY similarity(COALESCE(it.name, im.canonical_name), $1) DESC
		LIMIT $2`

	rows, err := r.pool.Query(ctx, q, query, limit, lang)
	if err != nil {
		return nil, fmt.Errorf("search ingredient_mappings: %w", err)
	}
	defer rows.Close()
	return collectMappings(rows)
}

// Count returns the total number of ingredient mappings.
func (r *Repository) Count(ctx context.Context) (int, error) {
	var n int
	if err := r.pool.QueryRow(ctx, `SELECT count(*) FROM ingredient_mappings`).Scan(&n); err != nil {
		return 0, fmt.Errorf("count ingredient_mappings: %w", err)
	}
	return n, nil
}

// ListMissingTranslation returns ingredients that have no translation for the
// given language, ordered by id.
func (r *Repository) ListMissingTranslation(ctx context.Context, lang string, limit, offset int) ([]*IngredientMapping, error) {
	query := `
		SELECT im.id, im.canonical_name, im.spoonacular_id, im.aliases,
			im.category, im.default_unit,
			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
			im.storage_days, im.created_at, im.updated_at
		FROM ingredient_mappings im
		WHERE NOT EXISTS (
		    SELECT 1 FROM ingredient_translations it
		    WHERE it.ingredient_id = im.id AND it.lang = $3
		)
		ORDER BY im.id
		LIMIT $1 OFFSET $2`

	rows, err := r.pool.Query(ctx, query, limit, offset, lang)
	if err != nil {
		return nil, fmt.Errorf("list missing translation (%s): %w", lang, err)
	}
	defer rows.Close()
	return collectMappings(rows)
}

// UpsertTranslation inserts or replaces a translation for an ingredient mapping.
func (r *Repository) UpsertTranslation(ctx context.Context, id, lang, name string, aliases json.RawMessage) error {
	query := `
		INSERT INTO ingredient_translations (ingredient_id, lang, name, aliases)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (ingredient_id, lang) DO UPDATE SET
			name    = EXCLUDED.name,
			aliases = EXCLUDED.aliases`

	if _, err := r.pool.Exec(ctx, query, id, lang, name, aliases); err != nil {
		return fmt.Errorf("upsert ingredient translation %s/%s: %w", id, lang, err)
	}
	return nil
}

// --- helpers ---

func scanMapping(row pgx.Row) (*IngredientMapping, error) {
	var m IngredientMapping
	var aliases []byte

	err := row.Scan(
		&m.ID, &m.CanonicalName, &m.SpoonacularID, &aliases,
		&m.Category, &m.DefaultUnit,
		&m.CaloriesPer100g, &m.ProteinPer100g, &m.FatPer100g, &m.CarbsPer100g, &m.FiberPer100g,
		&m.StorageDays, &m.CreatedAt, &m.UpdatedAt,
	)
	if err != nil {
		return nil, err
	}
	m.Aliases = json.RawMessage(aliases)
	return &m, nil
}

func collectMappings(rows pgx.Rows) ([]*IngredientMapping, error) {
	var result []*IngredientMapping
	for rows.Next() {
		var m IngredientMapping
		var aliases []byte
		if err := rows.Scan(
			&m.ID, &m.CanonicalName, &m.SpoonacularID, &aliases,
			&m.Category, &m.DefaultUnit,
			&m.CaloriesPer100g, &m.ProteinPer100g, &m.FatPer100g, &m.CarbsPer100g, &m.FiberPer100g,
			&m.StorageDays, &m.CreatedAt, &m.UpdatedAt,
		); err != nil {
			return nil, fmt.Errorf("scan mapping: %w", err)
		}
		m.Aliases = json.RawMessage(aliases)
		result = append(result, &m)
	}
	return result, rows.Err()
}