package dish

import (
	"context"
	"errors"
	"fmt"

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

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

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

// GetByID returns a dish with all its tag slugs and recipe variants.
// Text is resolved for the language in ctx (English fallback).
// Returns nil, nil if not found.
func (r *Repository) GetByID(ctx context.Context, id string) (*Dish, error) {
	lang := locale.FromContext(ctx)

	const q = `
		SELECT d.id,
			d.cuisine_slug, d.category_slug,
			COALESCE(dt.name,        d.name)        AS name,
			COALESCE(dt.description, d.description) AS description,
			d.image_url, d.avg_rating, d.review_count,
			d.created_at, d.updated_at
		FROM dishes d
		LEFT JOIN dish_translations dt ON dt.dish_id = d.id AND dt.lang = $2
		WHERE d.id = $1`

	row := r.pool.QueryRow(ctx, q, id, lang)
	dish, err := scanDish(row)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("get dish %s: %w", id, err)
	}

	if err := r.loadTags(ctx, dish); err != nil {
		return nil, err
	}
	if err := r.loadRecipes(ctx, dish, lang); err != nil {
		return nil, err
	}
	return dish, nil
}

// List returns all dishes with tag slugs (no recipe variants).
// Text is resolved for the language in ctx.
func (r *Repository) List(ctx context.Context) ([]*Dish, error) {
	lang := locale.FromContext(ctx)

	const q = `
		SELECT d.id,
			d.cuisine_slug, d.category_slug,
			COALESCE(dt.name,        d.name)        AS name,
			COALESCE(dt.description, d.description) AS description,
			d.image_url, d.avg_rating, d.review_count,
			d.created_at, d.updated_at
		FROM dishes d
		LEFT JOIN dish_translations dt ON dt.dish_id = d.id AND dt.lang = $1
		ORDER BY d.updated_at DESC`

	rows, err := r.pool.Query(ctx, q, lang)
	if err != nil {
		return nil, fmt.Errorf("list dishes: %w", err)
	}
	defer rows.Close()

	var dishes []*Dish
	for rows.Next() {
		d, err := scanDish(rows)
		if err != nil {
			return nil, fmt.Errorf("scan dish: %w", err)
		}
		dishes = append(dishes, d)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	// Load tags for each dish.
	for _, d := range dishes {
		if err := r.loadTags(ctx, d); err != nil {
			return nil, err
		}
	}
	return dishes, nil
}

// Create creates a new dish + recipe row from a CreateRequest.
// Returns the recipe ID to be used in menu_items or user_saved_recipes.
func (r *Repository) Create(ctx context.Context, req CreateRequest) (recipeID string, err error) {
	tx, err := r.pool.BeginTx(ctx, pgx.TxOptions{})
	if err != nil {
		return "", fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback(ctx) //nolint:errcheck

	// Resolve cuisine slug (empty string → NULL).
	cuisineSlug := nullableStr(req.CuisineSlug)

	// Insert dish.
	var dishID string
	err = tx.QueryRow(ctx, `
		INSERT INTO dishes (cuisine_slug, name, description, image_url)
		VALUES ($1, $2, NULLIF($3,''), NULLIF($4,''))
		RETURNING id`,
		cuisineSlug, req.Name, req.Description, req.ImageURL,
	).Scan(&dishID)
	if err != nil {
		return "", fmt.Errorf("insert dish: %w", err)
	}

	// Insert tags.
	for _, slug := range req.Tags {
		if _, err := tx.Exec(ctx,
			`INSERT INTO dish_tags (dish_id, tag_slug) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
			dishID, slug,
		); err != nil {
			return "", fmt.Errorf("insert dish tag %s: %w", slug, err)
		}
	}

	// Insert recipe.
	source := req.Source
	if source == "" {
		source = "ai"
	}
	difficulty := nullableStr(req.Difficulty)
	prepTime := nullableInt(req.PrepTimeMin)
	cookTime := nullableInt(req.CookTimeMin)
	servings := nullableInt(req.Servings)
	calories := nullableFloat(req.Calories)
	protein := nullableFloat(req.Protein)
	fat := nullableFloat(req.Fat)
	carbs := nullableFloat(req.Carbs)

	err = tx.QueryRow(ctx, `
		INSERT INTO recipes (dish_id, source, difficulty, prep_time_min, cook_time_min, servings,
			calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
		RETURNING id`,
		dishID, source, difficulty, prepTime, cookTime, servings,
		calories, protein, fat, carbs,
	).Scan(&recipeID)
	if err != nil {
		return "", fmt.Errorf("insert recipe: %w", err)
	}

	// Insert recipe_ingredients.
	for i, ing := range req.Ingredients {
		if _, err := tx.Exec(ctx, `
			INSERT INTO recipe_ingredients (recipe_id, name, amount, unit_code, is_optional, sort_order)
			VALUES ($1, $2, $3, NULLIF($4,''), $5, $6)`,
			recipeID, ing.Name, ing.Amount, ing.Unit, ing.IsOptional, i,
		); err != nil {
			return "", fmt.Errorf("insert ingredient %d: %w", i, err)
		}
	}

	// Insert recipe_steps.
	for _, s := range req.Steps {
		num := s.Number
		if num <= 0 {
			num = 1
		}
		if _, err := tx.Exec(ctx, `
			INSERT INTO recipe_steps (recipe_id, step_number, timer_seconds, description)
			VALUES ($1, $2, $3, $4)`,
			recipeID, num, s.TimerSeconds, s.Description,
		); err != nil {
			return "", fmt.Errorf("insert step %d: %w", num, err)
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return "", fmt.Errorf("commit: %w", err)
	}
	return recipeID, nil
}

// loadTags fills d.Tags with the slugs from dish_tags.
func (r *Repository) loadTags(ctx context.Context, d *Dish) error {
	rows, err := r.pool.Query(ctx,
		`SELECT tag_slug FROM dish_tags WHERE dish_id = $1 ORDER BY tag_slug`, d.ID)
	if err != nil {
		return fmt.Errorf("load tags for dish %s: %w", d.ID, err)
	}
	defer rows.Close()
	for rows.Next() {
		var slug string
		if err := rows.Scan(&slug); err != nil {
			return err
		}
		d.Tags = append(d.Tags, slug)
	}
	return rows.Err()
}

// loadRecipes fills d.Recipes with all recipe variants for the dish,
// including their relational ingredients and steps.
func (r *Repository) loadRecipes(ctx context.Context, d *Dish, lang string) error {
	rows, err := r.pool.Query(ctx, `
		SELECT r.id, r.dish_id, r.source, r.difficulty,
			r.prep_time_min, r.cook_time_min, r.servings,
			r.calories_per_serving, r.protein_per_serving, r.fat_per_serving,
			r.carbs_per_serving, r.fiber_per_serving,
			rt.notes,
			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.dish_id = $1
		ORDER BY r.created_at DESC`, d.ID, lang)
	if err != nil {
		return fmt.Errorf("load recipes for dish %s: %w", d.ID, err)
	}
	defer rows.Close()

	for rows.Next() {
		rec, err := scanRecipe(rows)
		if err != nil {
			return fmt.Errorf("scan recipe: %w", err)
		}
		d.Recipes = append(d.Recipes, *rec)
	}
	if err := rows.Err(); err != nil {
		return err
	}

	// Load ingredients and steps for each recipe.
	for i := range d.Recipes {
		if err := r.loadIngredients(ctx, &d.Recipes[i], lang); err != nil {
			return err
		}
		if err := r.loadSteps(ctx, &d.Recipes[i], lang); err != nil {
			return err
		}
	}
	return nil
}

// loadIngredients fills rec.Ingredients from recipe_ingredients.
func (r *Repository) loadIngredients(ctx context.Context, rec *Recipe, lang string) error {
	rows, err := r.pool.Query(ctx, `
		SELECT ri.id, ri.ingredient_id,
			COALESCE(rit.name, ri.name) AS name,
			ri.amount, ri.unit_code, ri.is_optional, ri.sort_order
		FROM recipe_ingredients ri
		LEFT JOIN recipe_ingredient_translations rit
			ON rit.ri_id = ri.id AND rit.lang = $2
		WHERE ri.recipe_id = $1
		ORDER BY ri.sort_order`, rec.ID, lang)
	if err != nil {
		return fmt.Errorf("load ingredients for recipe %s: %w", rec.ID, err)
	}
	defer rows.Close()

	for rows.Next() {
		var ing RecipeIngredient
		if err := rows.Scan(
			&ing.ID, &ing.IngredientID, &ing.Name,
			&ing.Amount, &ing.UnitCode, &ing.IsOptional, &ing.SortOrder,
		); err != nil {
			return fmt.Errorf("scan ingredient: %w", err)
		}
		rec.Ingredients = append(rec.Ingredients, ing)
	}
	return rows.Err()
}

// loadSteps fills rec.Steps from recipe_steps.
func (r *Repository) loadSteps(ctx context.Context, rec *Recipe, lang string) error {
	rows, err := r.pool.Query(ctx, `
		SELECT rs.id, rs.step_number,
			COALESCE(rst.description, rs.description) AS description,
			rs.timer_seconds, rs.image_url
		FROM recipe_steps rs
		LEFT JOIN recipe_step_translations rst
			ON rst.step_id = rs.id AND rst.lang = $2
		WHERE rs.recipe_id = $1
		ORDER BY rs.step_number`, rec.ID, lang)
	if err != nil {
		return fmt.Errorf("load steps for recipe %s: %w", rec.ID, err)
	}
	defer rows.Close()

	for rows.Next() {
		var s RecipeStep
		if err := rows.Scan(
			&s.ID, &s.StepNumber, &s.Description, &s.TimerSeconds, &s.ImageURL,
		); err != nil {
			return fmt.Errorf("scan step: %w", err)
		}
		rec.Steps = append(rec.Steps, s)
	}
	return rows.Err()
}

// --- scan helpers ---

type scannable interface {
	Scan(dest ...any) error
}

func scanDish(s scannable) (*Dish, error) {
	var d Dish
	err := s.Scan(
		&d.ID, &d.CuisineSlug, &d.CategorySlug,
		&d.Name, &d.Description, &d.ImageURL,
		&d.AvgRating, &d.ReviewCount,
		&d.CreatedAt, &d.UpdatedAt,
	)
	if err != nil {
		return nil, err
	}
	d.Tags = []string{}
	return &d, nil
}

func scanRecipe(s scannable) (*Recipe, error) {
	var rec Recipe
	err := s.Scan(
		&rec.ID, &rec.DishID, &rec.Source, &rec.Difficulty,
		&rec.PrepTimeMin, &rec.CookTimeMin, &rec.Servings,
		&rec.CaloriesPerServing, &rec.ProteinPerServing, &rec.FatPerServing,
		&rec.CarbsPerServing, &rec.FiberPerServing,
		&rec.Notes,
		&rec.CreatedAt, &rec.UpdatedAt,
	)
	if err != nil {
		return nil, err
	}
	rec.Ingredients = []RecipeIngredient{}
	rec.Steps = []RecipeStep{}
	return &rec, nil
}

// --- null helpers ---

func nullableStr(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}

func nullableInt(n int) *int {
	if n <= 0 {
		return nil
	}
	return &n
}

func nullableFloat(f float64) *float64 {
	if f <= 0 {
		return nil
	}
	return &f
}