package ingredient

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

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

// Repository handles persistence for ingredient_mappings.
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.
// Conflict is resolved on spoonacular_id when set; otherwise a simple insert is done.
func (r *Repository) Upsert(ctx context.Context, m *IngredientMapping) (*IngredientMapping, error) {
	query := `
		INSERT INTO ingredient_mappings (
			canonical_name, canonical_name_ru, 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, $12)
		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, canonical_name_ru, 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.CanonicalNameRu, 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.
// Returns nil, nil if not found.
func (r *Repository) GetBySpoonacularID(ctx context.Context, id int) (*IngredientMapping, error) {
	query := `
		SELECT id, canonical_name, canonical_name_ru, 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
		FROM ingredient_mappings
		WHERE spoonacular_id = $1`

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

// GetByID returns an ingredient mapping by UUID.
// Returns nil, nil if not found.
func (r *Repository) GetByID(ctx context.Context, id string) (*IngredientMapping, error) {
	query := `
		SELECT id, canonical_name, canonical_name_ru, 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
		FROM ingredient_mappings
		WHERE id = $1`

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

// 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
}

// ListUntranslated returns ingredients without a Russian name, ordered by id.
func (r *Repository) ListUntranslated(ctx context.Context, limit, offset int) ([]*IngredientMapping, error) {
	query := `
		SELECT id, canonical_name, canonical_name_ru, 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
		FROM ingredient_mappings
		WHERE canonical_name_ru IS NULL
		ORDER BY id
		LIMIT $1 OFFSET $2`

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

// UpdateTranslation saves the Russian name and adds Russian aliases.
func (r *Repository) UpdateTranslation(ctx context.Context, id, canonicalNameRu string, aliasesRu []string) error {
	// Merge new aliases into existing JSONB array without duplicates
	query := `
		UPDATE ingredient_mappings SET
			canonical_name_ru = $2,
			aliases = (
				SELECT jsonb_agg(DISTINCT elem)
				FROM (
					SELECT jsonb_array_elements(aliases) AS elem
					UNION
					SELECT to_jsonb(unnest) FROM unnest($3::text[]) AS unnest
				) sub
			),
			updated_at = now()
		WHERE id = $1`

	if _, err := r.pool.Exec(ctx, query, id, canonicalNameRu, aliasesRu); err != nil {
		return fmt.Errorf("update translation %s: %w", id, 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.CanonicalNameRu, &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.CanonicalNameRu, &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()
}