package repository

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"strings"

	domain "github.com/haydenhargreaves/Potion/internal/domain/recipe"
	"github.com/lib/pq"
)

type RecipeRepository struct {
	db *sql.DB
}

// Compile-time check to ensure the RecipeRepository implements domain.RecipeRepository
var _ domain.RecipeRepository = (*RecipeRepository)(nil)

// NewRecipeRepository creates a user repository object which is used by the user service to access
// the database. Any recipe related database operations will take place in this repository.
func NewRecipeRepository(db *sql.DB) domain.RecipeRepository {
	return &RecipeRepository{db: db}
}

// NOTE: This function modified the provided recipe with the new values, such as id and time stamp

// CreateRecipe creates a recipe in the database. The recipe provided should contain all data except
// time stamps and the ID; the database will fill them when the operation succeeds. Any errors will
// be bubbled to the caller. The recipe parameter is passed by reference and will therefore be updated
// directly and the new fields (ID, created) can be accessed upon success.
func (r *RecipeRepository) CreateRecipe(recipe *domain.Recipe) error {
	tx, err := r.db.Begin()
	if err != nil {
		tx.Rollback()
		return err
	}

	query := `INSERT INTO recipes (
			title, description, instructions, serves, difficulty,
			duration, category, ingredients, userid, modified, created
		) VALUES (
			$1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11
		) RETURNING id;`

	// NOTE: Data steps
	// cast duration to JSON
	// cast ingredients to JSON
	// cast category to string
	// use nil for the modified time

	durationJSON, err := json.Marshal(recipe.Duration)
	if err != nil {
		return err
	}

	ingredientsJSON, err := json.Marshal(recipe.Ingredients)
	if err != nil {
		return err
	}

	var id int
	if err = tx.QueryRow(
		query,
		recipe.Title,
		recipe.Description,
		pq.Array(recipe.Instructions),
		recipe.Serves,
		recipe.Difficulty,
		durationJSON,
		string(recipe.Category),
		ingredientsJSON,
		recipe.UserId,
		nil,
		recipe.Created,
	).Scan(&id); err != nil {
		tx.Rollback()
		return err
	}

	if err := tx.Commit(); err != nil {
		tx.Rollback()
		return err
	}

	// Set the new ID
	recipe.Id = id

	return nil
}

// GetRecipe gets a recipe from the database via its ID. The operation is wrapped in a transaction
// for added safety. The repository will not check for a nil result, instead the service will. Callers
// are responsible for protecting against double nil results. Any errors will be bubbled to the caller.
func (r *RecipeRepository) GetRecipe(id int) (*domain.Recipe, error) {
	tx, err := r.db.Begin()
	if err != nil {
		tx.Rollback()
		return nil, err
	}

	query := "SELECT * FROM recipes WHERE id = $1"

	var durationBytes []byte
	var ingredientBytes []byte

	var recipe domain.Recipe
	if err := tx.QueryRow(query, id).Scan(
		&recipe.Id,
		&recipe.Title,
		&recipe.Description,
		pq.Array(&recipe.Instructions),
		&recipe.Serves,
		&recipe.Difficulty,
		&durationBytes,
		&recipe.Category,
		&ingredientBytes,
		&recipe.UserId,
		&recipe.Modified,
		&recipe.Created,
	); err != nil {
		return nil, fmt.Errorf("Failed to location recipe in database: %s", err.Error())
	}

	if err := tx.Commit(); err != nil {
		tx.Rollback()
		return nil, err
	}

	// Parse duration
	if len(durationBytes) > 0 {
		var duration domain.RecipeDuration
		if err := json.Unmarshal(durationBytes, &duration); err != nil {
			return nil, fmt.Errorf("Failed to parse duration from database: %s", err.Error())
		}

		recipe.Duration = duration
	} else {
		recipe.Duration = domain.RecipeDuration{}
	}

	// Parse ingredient
	if len(ingredientBytes) > 0 {
		var ingredients []domain.RecipeIngredient
		if err := json.Unmarshal(ingredientBytes, &ingredients); err != nil {
			return nil, fmt.Errorf("Failed to parse ingredients from database: %s", err.Error())
		}

		recipe.Ingredients = ingredients
	} else {
		recipe.Ingredients = []domain.RecipeIngredient{}
	}

	return &recipe, nil
}

// isBitActive returns true when the bit at pos (0 indexed) is true.
func isBitActive(bits, pos int) bool {
	return (bits>>pos)&1 == 1
}

// SearchRecipes will search the recipe table using the provided filters and return an unbound list
// of recipes. The filters are fairly complex, they are stored as bit masks. A more details 
// description can be found in the recipe service implementation. Any errors will be bubbled to the 
// caller. 
// 
// TODO: Pagination is required, to provide infinite scroll.
func (r *RecipeRepository) SearchRecipes(filters domain.SearchFilters) ([]domain.Recipe, error) {
	tx, err := r.db.Begin()
	if err != nil {
		tx.Rollback()
		return nil, err
	}

	// Generate the query
	query := "SELECT * FROM recipes"

	// Compute meals type filters (there are 7 bits)
	var mealConditions []string
	for i := range 7 {
		if isBitActive(filters.MealType, i) {
			mealConditions = append(mealConditions, fmt.Sprintf("category = '%s'", domain.ParseMeal(i)))
		}
	}

	// Compute time filters (there are 5 bits)
	var timeConditions []string
	for i := range 5 {
		var cond string
		if isBitActive(filters.Time, i) {
			switch i {
			case 0:
				cond = "(duration->>'total')::int < 15"
			case 1:
				cond = "(duration->>'total')::int BETWEEN 15 AND 30"
			case 2:
				cond = "(duration->>'total')::int BETWEEN 30 AND 60"
			case 3:
				cond = "(duration->>'total')::int BETWEEN 60 AND 120"
			case 4:
				cond = "(duration->>'total')::int > 120"
			}
			timeConditions = append(timeConditions, cond)
		}
	}

	// Compute difficulty filters (there are 5 bits)
	var difficultyConditions []string
	for i := range 5 {
		if isBitActive(filters.Difficulty, i) {
			cond := fmt.Sprintf("difficulty = '%d'", i+1)
			difficultyConditions = append(difficultyConditions, cond)
		}
	}

	// Compute serving size filters (there are 5 bits)
	var servingConditions []string
	for i := range 5 {
		var cond string
		if isBitActive(filters.ServingSize, i) {
			switch i {
			case 0:
				cond = "serves BETWEEN 1 AND 2"
			case 1:
				cond = "serves BETWEEN 2 AND 4"
			case 2:
				cond = "serves BETWEEN 4 AND 6"
			case 3:
				cond = "serves BETWEEN 6 AND 8"
			case 4:
				cond = "serves > 8"
			}
			servingConditions = append(servingConditions, cond)
		}
	}

	// TODO: Title search somehow...

	// Merge condition strings
	mealString := fmt.Sprintf("(%s)", strings.Join(mealConditions, " OR "))
	timeString := fmt.Sprintf("(%s)", strings.Join(timeConditions, " OR "))
	difficultyString := fmt.Sprintf("(%s)", strings.Join(difficultyConditions, " OR "))
	servingString := fmt.Sprintf("(%s)", strings.Join(servingConditions, " OR "))

	// Combine condition strings
	var conditions []string
	if len(mealConditions) > 0 {
		conditions = append(conditions, mealString)
	}
	if len(timeConditions) > 0 {
		conditions = append(conditions, timeString)
	}
	if len(difficultyConditions) > 0 {
		conditions = append(conditions, difficultyString)
	}
	if len(servingConditions) > 0 {
		conditions = append(conditions, servingString)
	}

	// Convert and append conditions
	if len(conditions) > 0 {
		conditionsString := fmt.Sprintf("WHERE %s", strings.Join(conditions, " AND "))
		query = fmt.Sprintf("%s %s;", query, conditionsString)
	} else {
		query += ";"
	}

	fmt.Println(query)

	// Execute the query
	rows, err := tx.Query(query)
	if err != nil {
		return nil, fmt.Errorf("failed to query recipes: %w", err)
	}
	defer rows.Close()

	var recipes []domain.Recipe
	for rows.Next() {
		// Parsed values location
		var recipe domain.Recipe
		var durationBytes []byte
		var ingredientBytes []byte

		if err := rows.Scan(
			&recipe.Id,
			&recipe.Title,
			&recipe.Description,
			pq.Array(&recipe.Instructions),
			&recipe.Serves,
			&recipe.Difficulty,
			&durationBytes,
			&recipe.Category,
			&ingredientBytes,
			&recipe.UserId,
			&recipe.Modified,
			&recipe.Created,
		); err != nil {
			return nil, fmt.Errorf("failed to scan recipe row: %w", err)
		}

		// Parse duration from bytes
		if len(durationBytes) > 0 {
			var duration domain.RecipeDuration
			if err := json.Unmarshal(durationBytes, &duration); err != nil {
				return nil, fmt.Errorf("failed to parse duration for recipe ID %d: %w", recipe.Id, err)
			}
			recipe.Duration = duration
		} else {
			recipe.Duration = domain.RecipeDuration{}
		}

		// Parse ingredients from bytes
		if len(ingredientBytes) > 0 {
			var ingredients []domain.RecipeIngredient
			if err := json.Unmarshal(ingredientBytes, &ingredients); err != nil {
				return nil, fmt.Errorf("failed to parse ingredients for recipe ID %d: %w", recipe.Id, err)
			}
			recipe.Ingredients = ingredients
		} else {
			recipe.Ingredients = []domain.RecipeIngredient{}
		}

		recipes = append(recipes, recipe)
	}

	if err := tx.Commit(); err != nil {
		tx.Rollback()
		return nil, err
	}

	return recipes, nil
}