package savedrecipe

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

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

// Repository handles persistence for user_saved_recipes.
type Repository struct {
	pool     *pgxpool.Pool
	dishRepo *dish.Repository
}

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

// Save bookmarks a recipe for the user.
// If req.RecipeID is set, that existing catalog recipe is bookmarked.
// Otherwise a new dish + recipe is created from the supplied fields.
func (r *Repository) Save(ctx context.Context, userID string, req SaveRequest) (*UserSavedRecipe, error) {
	recipeID := req.RecipeID

	if recipeID == "" {
		// Build a dish.CreateRequest from the save body.
		cr := dish.CreateRequest{
			Name:        req.Title,
			Description: req.Description,
			CuisineSlug: mapCuisineSlug(req.Cuisine),
			ImageURL:    req.ImageURL,
			Source:      req.Source,
			Difficulty:  req.Difficulty,
			PrepTimeMin: req.PrepTimeMin,
			CookTimeMin: req.CookTimeMin,
			Servings:    req.Servings,
		}

		// Unmarshal ingredients.
		if req.Ingredients != nil {
			switch v := req.Ingredients.(type) {
			case []interface{}:
				for i, item := range v {
					m, ok := item.(map[string]interface{})
					if !ok {
						continue
					}
					ing := dish.IngredientInput{
						Name:   strVal(m["name"]),
						Amount: floatVal(m["amount"]),
						Unit:   strVal(m["unit"]),
					}
					cr.Ingredients = append(cr.Ingredients, ing)
					_ = i
				}
			case json.RawMessage:
				var items []dish.IngredientInput
				if err := json.Unmarshal(v, &items); err == nil {
					cr.Ingredients = items
				}
			}
		}

		// Unmarshal steps.
		if req.Steps != nil {
			switch v := req.Steps.(type) {
			case []interface{}:
				for i, item := range v {
					m, ok := item.(map[string]interface{})
					if !ok {
						continue
					}
					num := int(floatVal(m["number"]))
					if num <= 0 {
						num = i + 1
					}
					step := dish.StepInput{
						Number:      num,
						Description: strVal(m["description"]),
					}
					cr.Steps = append(cr.Steps, step)
				}
			case json.RawMessage:
				var items []dish.StepInput
				if err := json.Unmarshal(v, &items); err == nil {
					cr.Steps = items
				}
			}
		}

		// Unmarshal tags.
		if req.Tags != nil {
			switch v := req.Tags.(type) {
			case []interface{}:
				for _, t := range v {
					if s, ok := t.(string); ok {
						cr.Tags = append(cr.Tags, s)
					}
				}
			case json.RawMessage:
				var items []string
				if err := json.Unmarshal(v, &items); err == nil {
					cr.Tags = items
				}
			}
		}

		// Unmarshal nutrition.
		if req.Nutrition != nil {
			switch v := req.Nutrition.(type) {
			case map[string]interface{}:
				cr.Calories = floatVal(v["calories"])
				cr.Protein = floatVal(v["protein_g"])
				cr.Fat = floatVal(v["fat_g"])
				cr.Carbs = floatVal(v["carbs_g"])
			case json.RawMessage:
				var nut struct {
					Calories float64 `json:"calories"`
					Protein  float64 `json:"protein_g"`
					Fat      float64 `json:"fat_g"`
					Carbs    float64 `json:"carbs_g"`
				}
				if err := json.Unmarshal(v, &nut); err == nil {
					cr.Calories = nut.Calories
					cr.Protein = nut.Protein
					cr.Fat = nut.Fat
					cr.Carbs = nut.Carbs
				}
			}
		}

		var err error
		recipeID, err = r.dishRepo.Create(ctx, cr)
		if err != nil {
			return nil, fmt.Errorf("create dish+recipe: %w", err)
		}
	}

	// Insert bookmark.
	const q = `
		INSERT INTO user_saved_recipes (user_id, recipe_id)
		VALUES ($1, $2)
		ON CONFLICT (user_id, recipe_id) DO UPDATE SET saved_at = now()
		RETURNING id, user_id, recipe_id, saved_at`

	var usr UserSavedRecipe
	err := r.pool.QueryRow(ctx, q, userID, recipeID).Scan(
		&usr.ID, &usr.UserID, &usr.RecipeID, &usr.SavedAt,
	)
	if err != nil {
		return nil, fmt.Errorf("insert bookmark: %w", err)
	}

	return r.enrichOne(ctx, &usr)
}

// List returns all bookmarked recipes for userID ordered by saved_at DESC.
func (r *Repository) List(ctx context.Context, userID string) ([]*UserSavedRecipe, error) {
	lang := locale.FromContext(ctx)
	const q = `
		SELECT usr.id, usr.user_id, usr.recipe_id, usr.saved_at,
			COALESCE(dt.name,        d.name)        AS dish_name,
			COALESCE(dt.description, d.description) AS description,
			d.image_url, d.cuisine_slug,
			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
		FROM user_saved_recipes usr
		JOIN recipes r ON r.id = usr.recipe_id
		JOIN dishes  d ON d.id = r.dish_id
		LEFT JOIN dish_translations dt ON dt.dish_id = d.id AND dt.lang = $2
		WHERE usr.user_id = $1
		ORDER BY usr.saved_at DESC`

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

	var result []*UserSavedRecipe
	for rows.Next() {
		rec, err := scanUSR(rows)
		if err != nil {
			return nil, fmt.Errorf("scan saved recipe: %w", err)
		}
		if err := r.loadTags(ctx, rec); err != nil {
			return nil, err
		}
		if err := r.loadIngredients(ctx, rec, lang); err != nil {
			return nil, err
		}
		if err := r.loadSteps(ctx, rec, lang); err != nil {
			return nil, err
		}
		result = append(result, rec)
	}
	return result, rows.Err()
}

// GetByID returns a bookmarked recipe by its bookmark ID for userID.
// Returns nil, nil if not found.
func (r *Repository) GetByID(ctx context.Context, userID, id string) (*UserSavedRecipe, error) {
	lang := locale.FromContext(ctx)
	const q = `
		SELECT usr.id, usr.user_id, usr.recipe_id, usr.saved_at,
			COALESCE(dt.name,        d.name)        AS dish_name,
			COALESCE(dt.description, d.description) AS description,
			d.image_url, d.cuisine_slug,
			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
		FROM user_saved_recipes usr
		JOIN recipes r ON r.id = usr.recipe_id
		JOIN dishes  d ON d.id = r.dish_id
		LEFT JOIN dish_translations dt ON dt.dish_id = d.id AND dt.lang = $3
		WHERE usr.id = $1 AND usr.user_id = $2`

	rec, err := scanUSR(r.pool.QueryRow(ctx, q, id, userID, lang))
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	if err := r.loadTags(ctx, rec); err != nil {
		return nil, err
	}
	if err := r.loadIngredients(ctx, rec, lang); err != nil {
		return nil, err
	}
	if err := r.loadSteps(ctx, rec, lang); err != nil {
		return nil, err
	}
	return rec, nil
}

// Delete removes a bookmark.
func (r *Repository) Delete(ctx context.Context, userID, id string) error {
	tag, err := r.pool.Exec(ctx,
		`DELETE FROM user_saved_recipes WHERE id = $1 AND user_id = $2`, id, userID)
	if err != nil {
		return fmt.Errorf("delete saved recipe: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

// --- helpers ---

func (r *Repository) enrichOne(ctx context.Context, usr *UserSavedRecipe) (*UserSavedRecipe, error) {
	lang := locale.FromContext(ctx)
	const q = `
		SELECT COALESCE(dt.name, d.name)               AS dish_name,
			COALESCE(dt.description, d.description) AS description,
			d.image_url, d.cuisine_slug,
			rec.difficulty, rec.prep_time_min, rec.cook_time_min, rec.servings,
			rec.calories_per_serving, rec.protein_per_serving,
			rec.fat_per_serving, rec.carbs_per_serving
		FROM recipes rec
		JOIN dishes d ON d.id = rec.dish_id
		LEFT JOIN dish_translations dt ON dt.dish_id = d.id AND dt.lang = $2
		WHERE rec.id = $1`

	row := r.pool.QueryRow(ctx, q, usr.RecipeID, lang)
	if err := row.Scan(
		&usr.DishName, &usr.Description, &usr.ImageURL, &usr.CuisineSlug,
		&usr.Difficulty, &usr.PrepTimeMin, &usr.CookTimeMin, &usr.Servings,
		&usr.CaloriesPerServing, &usr.ProteinPerServing, &usr.FatPerServing, &usr.CarbsPerServing,
	); err != nil {
		return nil, fmt.Errorf("enrich saved recipe: %w", err)
	}
	if err := r.loadTags(ctx, usr); err != nil {
		return nil, err
	}
	if err := r.loadIngredients(ctx, usr, lang); err != nil {
		return nil, err
	}
	return usr, r.loadSteps(ctx, usr, lang)
}

func (r *Repository) loadTags(ctx context.Context, usr *UserSavedRecipe) error {
	rows, err := r.pool.Query(ctx, `
		SELECT dt.tag_slug
		FROM dish_tags dt
		JOIN recipes rec ON rec.dish_id = dt.dish_id
		JOIN user_saved_recipes usr ON usr.recipe_id = rec.id
		WHERE usr.id = $1
		ORDER BY dt.tag_slug`, usr.ID)
	if err != nil {
		return fmt.Errorf("load tags for saved recipe %s: %w", usr.ID, err)
	}
	defer rows.Close()
	usr.Tags = []string{}
	for rows.Next() {
		var slug string
		if err := rows.Scan(&slug); err != nil {
			return err
		}
		usr.Tags = append(usr.Tags, slug)
	}
	return rows.Err()
}

func (r *Repository) loadIngredients(ctx context.Context, usr *UserSavedRecipe, lang string) error {
	rows, err := r.pool.Query(ctx, `
		SELECT COALESCE(rit.name, ri.name) AS name,
			ri.amount, ri.unit_code, ri.is_optional
		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`, usr.RecipeID, lang)
	if err != nil {
		return fmt.Errorf("load ingredients for saved recipe %s: %w", usr.ID, err)
	}
	defer rows.Close()
	usr.Ingredients = []RecipeIngredient{}
	for rows.Next() {
		var ing RecipeIngredient
		if err := rows.Scan(&ing.Name, &ing.Amount, &ing.UnitCode, &ing.IsOptional); err != nil {
			return err
		}
		usr.Ingredients = append(usr.Ingredients, ing)
	}
	return rows.Err()
}

func (r *Repository) loadSteps(ctx context.Context, usr *UserSavedRecipe, lang string) error {
	rows, err := r.pool.Query(ctx, `
		SELECT rs.step_number,
			COALESCE(rst.description, rs.description) AS description,
			rs.timer_seconds
		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`, usr.RecipeID, lang)
	if err != nil {
		return fmt.Errorf("load steps for saved recipe %s: %w", usr.ID, err)
	}
	defer rows.Close()
	usr.Steps = []RecipeStep{}
	for rows.Next() {
		var s RecipeStep
		if err := rows.Scan(&s.StepNumber, &s.Description, &s.TimerSeconds); err != nil {
			return err
		}
		usr.Steps = append(usr.Steps, s)
	}
	return rows.Err()
}

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

func scanUSR(s rowScanner) (*UserSavedRecipe, error) {
	var r UserSavedRecipe
	err := s.Scan(
		&r.ID, &r.UserID, &r.RecipeID, &r.SavedAt,
		&r.DishName, &r.Description, &r.ImageURL, &r.CuisineSlug,
		&r.Difficulty, &r.PrepTimeMin, &r.CookTimeMin, &r.Servings,
		&r.CaloriesPerServing, &r.ProteinPerServing, &r.FatPerServing, &r.CarbsPerServing,
	)
	return &r, err
}

// mapCuisineSlug maps a free-form cuisine string (from Gemini) to a known slug.
// Falls back to "other".
func mapCuisineSlug(cuisine string) string {
	known := map[string]string{
		"russian":       "russian",
		"italian":       "italian",
		"french":        "french",
		"chinese":       "chinese",
		"japanese":      "japanese",
		"korean":        "korean",
		"mexican":       "mexican",
		"mediterranean": "mediterranean",
		"indian":        "indian",
		"thai":          "thai",
		"american":      "american",
		"georgian":      "georgian",
		"spanish":       "spanish",
		"german":        "german",
		"middle_eastern":"middle_eastern",
		"turkish":       "turkish",
		"greek":         "greek",
		"vietnamese":    "vietnamese",
		"asian":         "other",
		"european":      "other",
	}
	if s, ok := known[cuisine]; ok {
		return s
	}
	return "other"
}

func strVal(v interface{}) string {
	if s, ok := v.(string); ok {
		return s
	}
	return ""
}

func floatVal(v interface{}) float64 {
	switch n := v.(type) {
	case float64:
		return n
	case int:
		return float64(n)
	}
	return 0
}