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 ingredients 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 (English canonical content).
// Conflict is resolved on canonical_name.
func (r *Repository) Upsert(ctx context.Context, m *IngredientMapping) (*IngredientMapping, error) {
	query := `
		INSERT INTO ingredients (
			canonical_name,
			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)
		ON CONFLICT (canonical_name) DO UPDATE SET
			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, 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.Category, m.DefaultUnit,
		m.CaloriesPer100g, m.ProteinPer100g, m.FatPer100g, m.CarbsPer100g, m.FiberPer100g,
		m.StorageDays,
	)
	return scanMappingWrite(row)
}

// GetByID returns an ingredient by UUID.
// CanonicalName and aliases are 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.category,
			COALESCE(ict.name, im.category)      AS category_name,
			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,
			COALESCE(al.aliases, '[]'::json)     AS aliases
		FROM ingredients im
		LEFT JOIN ingredient_translations it
			ON it.ingredient_id = im.id AND it.lang = $2
		LEFT JOIN ingredient_category_translations ict
			ON ict.category_slug = im.category AND ict.lang = $2
		LEFT JOIN LATERAL (
			SELECT json_agg(ia.alias ORDER BY ia.alias) AS aliases
			FROM ingredient_aliases ia
			WHERE ia.ingredient_id = im.id AND ia.lang = $2
		) al ON true
		WHERE im.id = $1`

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

// FuzzyMatch finds the single best matching ingredient 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 ingredients matching the query string.
// Searches aliases table and translated names for the language in ctx.
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.category,
			COALESCE(ict.name, im.category)      AS category_name,
			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,
			COALESCE(al.aliases, '[]'::json)     AS aliases
		FROM ingredients im
		LEFT JOIN ingredient_translations it
			ON it.ingredient_id = im.id AND it.lang = $3
		LEFT JOIN ingredient_category_translations ict
			ON ict.category_slug = im.category AND ict.lang = $3
		LEFT JOIN LATERAL (
			SELECT json_agg(ia.alias ORDER BY ia.alias) AS aliases
			FROM ingredient_aliases ia
			WHERE ia.ingredient_id = im.id AND ia.lang = $3
		) al ON true
		WHERE EXISTS (
			SELECT 1 FROM ingredient_aliases ia
			WHERE ia.ingredient_id = im.id
			  AND (ia.lang = $3 OR ia.lang = 'en')
			  AND ia.alias ILIKE '%' || $1 || '%'
		)
		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 ingredients: %w", err)
	}
	defer rows.Close()
	return collectMappingsRead(rows)
}

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

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

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

// UpsertAliases inserts aliases for a given ingredient and language.
// Each alias is inserted with ON CONFLICT DO NOTHING, so duplicates are skipped.
func (r *Repository) UpsertAliases(ctx context.Context, id, lang string, aliases []string) error {
	if len(aliases) == 0 {
		return nil
	}
	batch := &pgx.Batch{}
	for _, alias := range aliases {
		batch.Queue(
			`INSERT INTO ingredient_aliases (ingredient_id, lang, alias) VALUES ($1, $2, $3) ON CONFLICT DO NOTHING`,
			id, lang, alias,
		)
	}
	results := r.pool.SendBatch(ctx, batch)
	defer results.Close()
	for range aliases {
		if _, err := results.Exec(); err != nil {
			return fmt.Errorf("upsert ingredient alias %s/%s: %w", id, lang, err)
		}
	}
	return nil
}

// UpsertCategoryTranslation inserts or replaces a localized category name.
func (r *Repository) UpsertCategoryTranslation(ctx context.Context, slug, lang, name string) error {
	query := `
		INSERT INTO ingredient_category_translations (category_slug, lang, name)
		VALUES ($1, $2, $3)
		ON CONFLICT (category_slug, lang) DO UPDATE SET name = EXCLUDED.name`

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

// --- scan helpers ---

// scanMappingWrite scans rows from Upsert / ListMissingTranslation queries
// (no aliases lateral join, no category_name).
func scanMappingWrite(row pgx.Row) (*IngredientMapping, error) {
	var m IngredientMapping
	err := row.Scan(
		&m.ID, &m.CanonicalName, &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("[]")
	return &m, nil
}

// scanMappingRead scans rows from GetByID / Search queries
// (includes category_name and aliases lateral join).
func scanMappingRead(row pgx.Row) (*IngredientMapping, error) {
	var m IngredientMapping
	var aliases []byte
	err := row.Scan(
		&m.ID, &m.CanonicalName, &m.Category, &m.CategoryName, &m.DefaultUnit,
		&m.CaloriesPer100g, &m.ProteinPer100g, &m.FatPer100g, &m.CarbsPer100g, &m.FiberPer100g,
		&m.StorageDays, &m.CreatedAt, &m.UpdatedAt, &aliases,
	)
	if err != nil {
		return nil, err
	}
	m.Aliases = json.RawMessage(aliases)
	return &m, nil
}

func collectMappingsWrite(rows pgx.Rows) ([]*IngredientMapping, error) {
	var result []*IngredientMapping
	for rows.Next() {
		var m IngredientMapping
		if err := rows.Scan(
			&m.ID, &m.CanonicalName, &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("[]")
		result = append(result, &m)
	}
	return result, rows.Err()
}

func collectMappingsRead(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.Category, &m.CategoryName, &m.DefaultUnit,
			&m.CaloriesPer100g, &m.ProteinPer100g, &m.FatPer100g, &m.CarbsPer100g, &m.FiberPer100g,
			&m.StorageDays, &m.CreatedAt, &m.UpdatedAt, &aliases,
		); err != nil {
			return nil, fmt.Errorf("scan mapping: %w", err)
		}
		m.Aliases = json.RawMessage(aliases)
		result = append(result, &m)
	}
	return result, rows.Err()
}