package recipe

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 recipes 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 a recipe (English canonical content only).
// Conflict is resolved on spoonacular_id.
func (r *Repository) Upsert(ctx context.Context, recipe *Recipe) (*Recipe, error) {
	query := `
		INSERT INTO recipes (
			source, spoonacular_id,
			title, description,
			cuisine, difficulty, prep_time_min, cook_time_min, servings, image_url,
			calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving, fiber_per_serving,
			ingredients, steps, tags
		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18)
		ON CONFLICT (spoonacular_id) DO UPDATE SET
			title                = EXCLUDED.title,
			description          = EXCLUDED.description,
			cuisine              = EXCLUDED.cuisine,
			difficulty           = EXCLUDED.difficulty,
			prep_time_min        = EXCLUDED.prep_time_min,
			cook_time_min        = EXCLUDED.cook_time_min,
			servings             = EXCLUDED.servings,
			image_url            = EXCLUDED.image_url,
			calories_per_serving = EXCLUDED.calories_per_serving,
			protein_per_serving  = EXCLUDED.protein_per_serving,
			fat_per_serving      = EXCLUDED.fat_per_serving,
			carbs_per_serving    = EXCLUDED.carbs_per_serving,
			fiber_per_serving    = EXCLUDED.fiber_per_serving,
			ingredients          = EXCLUDED.ingredients,
			steps                = EXCLUDED.steps,
			tags                 = EXCLUDED.tags,
			updated_at           = now()
		RETURNING id, source, spoonacular_id,
			title, description,
			cuisine, difficulty, prep_time_min, cook_time_min, servings, image_url,
			calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving, fiber_per_serving,
			ingredients, steps, tags,
			avg_rating, review_count, created_by, created_at, updated_at`

	row := r.pool.QueryRow(ctx, query,
		recipe.Source, recipe.SpoonacularID,
		recipe.Title, recipe.Description,
		recipe.Cuisine, recipe.Difficulty, recipe.PrepTimeMin, recipe.CookTimeMin, recipe.Servings, recipe.ImageURL,
		recipe.CaloriesPerServing, recipe.ProteinPerServing, recipe.FatPerServing, recipe.CarbsPerServing, recipe.FiberPerServing,
		recipe.Ingredients, recipe.Steps, recipe.Tags,
	)
	return scanRecipe(row)
}

// GetByID returns a recipe by UUID, with content resolved for the language
// stored in ctx (falls back to English when no translation exists).
// Returns nil, nil if not found.
func (r *Repository) GetByID(ctx context.Context, id string) (*Recipe, error) {
	lang := locale.FromContext(ctx)
	query := `
		SELECT r.id, r.source, r.spoonacular_id,
			COALESCE(rt.title,       r.title)       AS title,
			COALESCE(rt.description, r.description) AS description,
			r.cuisine, r.difficulty, r.prep_time_min, r.cook_time_min, r.servings, r.image_url,
			r.calories_per_serving, r.protein_per_serving, r.fat_per_serving, r.carbs_per_serving, r.fiber_per_serving,
			COALESCE(rt.ingredients, r.ingredients) AS ingredients,
			COALESCE(rt.steps,       r.steps)       AS steps,
			r.tags,
			r.avg_rating, r.review_count, r.created_by, r.created_at, r.updated_at
		FROM recipes r
		LEFT JOIN recipe_translations rt ON rt.recipe_id = r.id AND rt.lang = $2
		WHERE r.id = $1`

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

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

// ListMissingTranslation returns Spoonacular recipes that have no translation
// for the given language, ordered by review_count DESC.
func (r *Repository) ListMissingTranslation(ctx context.Context, lang string, limit, offset int) ([]*Recipe, error) {
	query := `
		SELECT id, source, spoonacular_id,
			title, description,
			cuisine, difficulty, prep_time_min, cook_time_min, servings, image_url,
			calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving, fiber_per_serving,
			ingredients, steps, tags,
			avg_rating, review_count, created_by, created_at, updated_at
		FROM recipes
		WHERE source = 'spoonacular'
		  AND NOT EXISTS (
		      SELECT 1 FROM recipe_translations rt
		      WHERE rt.recipe_id = recipes.id AND rt.lang = $3
		  )
		ORDER BY review_count DESC
		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 collectRecipes(rows)
}

// UpsertTranslation inserts or replaces a recipe translation for a specific language.
func (r *Repository) UpsertTranslation(
	ctx context.Context,
	id, lang string,
	title, description *string,
	ingredients, steps json.RawMessage,
) error {
	query := `
		INSERT INTO recipe_translations (recipe_id, lang, title, description, ingredients, steps)
		VALUES ($1, $2, $3, $4, $5, $6)
		ON CONFLICT (recipe_id, lang) DO UPDATE SET
			title       = EXCLUDED.title,
			description = EXCLUDED.description,
			ingredients = EXCLUDED.ingredients,
			steps       = EXCLUDED.steps`

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

// --- helpers ---

func scanRecipe(row pgx.Row) (*Recipe, error) {
	var rec Recipe
	var ingredients, steps, tags []byte

	err := row.Scan(
		&rec.ID, &rec.Source, &rec.SpoonacularID,
		&rec.Title, &rec.Description,
		&rec.Cuisine, &rec.Difficulty, &rec.PrepTimeMin, &rec.CookTimeMin, &rec.Servings, &rec.ImageURL,
		&rec.CaloriesPerServing, &rec.ProteinPerServing, &rec.FatPerServing, &rec.CarbsPerServing, &rec.FiberPerServing,
		&ingredients, &steps, &tags,
		&rec.AvgRating, &rec.ReviewCount, &rec.CreatedBy, &rec.CreatedAt, &rec.UpdatedAt,
	)
	if err != nil {
		return nil, err
	}
	rec.Ingredients = json.RawMessage(ingredients)
	rec.Steps = json.RawMessage(steps)
	rec.Tags = json.RawMessage(tags)
	return &rec, nil
}

func collectRecipes(rows pgx.Rows) ([]*Recipe, error) {
	var result []*Recipe
	for rows.Next() {
		var rec Recipe
		var ingredients, steps, tags []byte
		if err := rows.Scan(
			&rec.ID, &rec.Source, &rec.SpoonacularID,
			&rec.Title, &rec.Description,
			&rec.Cuisine, &rec.Difficulty, &rec.PrepTimeMin, &rec.CookTimeMin, &rec.Servings, &rec.ImageURL,
			&rec.CaloriesPerServing, &rec.ProteinPerServing, &rec.FatPerServing, &rec.CarbsPerServing, &rec.FiberPerServing,
			&ingredients, &steps, &tags,
			&rec.AvgRating, &rec.ReviewCount, &rec.CreatedBy, &rec.CreatedAt, &rec.UpdatedAt,
		); err != nil {
			return nil, fmt.Errorf("scan recipe: %w", err)
		}
		rec.Ingredients = json.RawMessage(ingredients)
		rec.Steps = json.RawMessage(steps)
		rec.Tags = json.RawMessage(tags)
		result = append(result, &rec)
	}
	return result, rows.Err()
}