package repository

import (
	"database/sql"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/daniil/homelab-api/internal/model"
	"github.com/jmoiron/sqlx"
)

var ErrFinanceCategoryNotFound = errors.New("finance category not found")
var ErrFinanceTransactionNotFound = errors.New("finance transaction not found")

type FinanceRepository struct {
	db *sqlx.DB
}

func NewFinanceRepository(db *sqlx.DB) *FinanceRepository {
	return &FinanceRepository{db: db}
}

// --- Categories ---

func (r *FinanceRepository) CreateCategory(cat *model.FinanceCategory) error {
	query := `INSERT INTO finance_categories (user_id, name, emoji, type, budget, color, sort_order)
		VALUES ($1, $2, $3, $4, $5, $6, $7) RETURNING id, created_at`
	return r.db.QueryRow(query, cat.UserID, cat.Name, cat.Emoji, cat.Type, cat.Budget, cat.Color, cat.SortOrder).
		Scan(&cat.ID, &cat.CreatedAt)
}

func (r *FinanceRepository) ListCategories(userID int64) ([]model.FinanceCategory, error) {
	query := `SELECT id, user_id, name, emoji, type, budget, color, sort_order, created_at
		FROM finance_categories WHERE user_id = $1 ORDER BY sort_order, id`
	rows, err := r.db.Query(query, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var cats []model.FinanceCategory
	for rows.Next() {
		var c model.FinanceCategory
		if err := rows.Scan(&c.ID, &c.UserID, &c.Name, &c.Emoji, &c.Type, &c.Budget, &c.Color, &c.SortOrder, &c.CreatedAt); err != nil {
			return nil, err
		}
		c.ProcessForJSON()
		cats = append(cats, c)
	}
	return cats, nil
}

func (r *FinanceRepository) GetCategory(id, userID int64) (*model.FinanceCategory, error) {
	var c model.FinanceCategory
	query := `SELECT id, user_id, name, emoji, type, budget, color, sort_order, created_at
		FROM finance_categories WHERE id = $1 AND user_id = $2`
	err := r.db.QueryRow(query, id, userID).Scan(&c.ID, &c.UserID, &c.Name, &c.Emoji, &c.Type, &c.Budget, &c.Color, &c.SortOrder, &c.CreatedAt)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrFinanceCategoryNotFound
		}
		return nil, err
	}
	c.ProcessForJSON()
	return &c, nil
}

func (r *FinanceRepository) UpdateCategory(cat *model.FinanceCategory) error {
	query := `UPDATE finance_categories SET name=$2, emoji=$3, type=$4, budget=$5, color=$6, sort_order=$7
		WHERE id=$1 AND user_id=$8`
	result, err := r.db.Exec(query, cat.ID, cat.Name, cat.Emoji, cat.Type, cat.Budget, cat.Color, cat.SortOrder, cat.UserID)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrFinanceCategoryNotFound
	}
	return nil
}

func (r *FinanceRepository) DeleteCategory(id, userID int64) error {
	result, err := r.db.Exec(`DELETE FROM finance_categories WHERE id=$1 AND user_id=$2`, id, userID)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrFinanceCategoryNotFound
	}
	return nil
}

func (r *FinanceRepository) SeedDefaultCategories(userID int64) error {
	type cat struct {
		emoji, name, typ, color string
	}
	defaults := []cat{
		{"🏠", "Жильё", "expense", "#ef4444"},
		{"🍔", "Еда", "expense", "#f97316"},
		{"🚗", "Транспорт", "expense", "#6366f1"},
		{"👕", "Одежда", "expense", "#8b5cf6"},
		{"🏥", "Здоровье", "expense", "#22c55e"},
		{"🎮", "Развлечения", "expense", "#ec4899"},
		{"📱", "Связь / Подписки", "expense", "#0ea5e9"},
		{"✈️", "Путешествия", "expense", "#14b8a6"},
		{"🎁", "Подарки", "expense", "#a855f7"},
		{"🛒", "Бытовое", "expense", "#64748b"},
		{"🛍️", "Маркетплейсы", "expense", "#F7B538"},
		{"💎", "Накопления", "expense", "#0D4F4F"},
		{"📦", "Другое", "expense", "#78716c"},
		{"💰", "Зарплата", "income", "#22c55e"},
		{"💼", "Фриланс", "income", "#6366f1"},
		{"📈", "Другой доход", "income", "#0ea5e9"},
	}
	for i, c := range defaults {
		_, err := r.db.Exec(`INSERT INTO finance_categories (user_id, name, emoji, type, color, sort_order) VALUES ($1,$2,$3,$4,$5,$6)`,
			userID, c.name, c.emoji, c.typ, c.color, i)
		if err != nil {
			return err
		}
	}
	return nil
}

// --- Transactions ---

func (r *FinanceRepository) CreateTransaction(tx *model.FinanceTransaction) error {
	query := `INSERT INTO finance_transactions (user_id, category_id, type, amount, description, date)
		VALUES ($1,$2,$3,$4,$5,$6) RETURNING id, created_at`
	return r.db.QueryRow(query, tx.UserID, tx.CategoryID, tx.Type, tx.Amount, tx.Description, tx.Date).
		Scan(&tx.ID, &tx.CreatedAt)
}

func (r *FinanceRepository) ListTransactions(userID int64, month, year int, categoryID *int64, txType, search string, limit, offset int) ([]model.FinanceTransaction, error) {
	args := []interface{}{userID}
	conditions := []string{"t.user_id = $1"}
	argIdx := 2

	if month > 0 && year > 0 {
		conditions = append(conditions, fmt.Sprintf("EXTRACT(MONTH FROM t.date) = $%d AND EXTRACT(YEAR FROM t.date) = $%d", argIdx, argIdx+1))
		args = append(args, month, year)
		argIdx += 2
	}
	if categoryID != nil {
		conditions = append(conditions, fmt.Sprintf("t.category_id = $%d", argIdx))
		args = append(args, *categoryID)
		argIdx++
	}
	if txType != "" {
		conditions = append(conditions, fmt.Sprintf("t.type = $%d", argIdx))
		args = append(args, txType)
		argIdx++
	}
	if search != "" {
		conditions = append(conditions, fmt.Sprintf("t.description ILIKE $%d", argIdx))
		args = append(args, "%"+search+"%")
		argIdx++
	}

	if limit <= 0 {
		limit = 50
	}

	query := fmt.Sprintf(`SELECT t.id, t.user_id, t.category_id, t.type, t.amount, t.description, t.date, t.created_at,
		COALESCE(c.name,'') as category_name, COALESCE(c.emoji,'') as category_emoji
		FROM finance_transactions t
		LEFT JOIN finance_categories c ON c.id = t.category_id
		WHERE %s ORDER BY t.date DESC, t.id DESC LIMIT %d OFFSET %d`,
		strings.Join(conditions, " AND "), limit, offset)

	rows, err := r.db.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var txs []model.FinanceTransaction
	for rows.Next() {
		var t model.FinanceTransaction
		if err := rows.Scan(&t.ID, &t.UserID, &t.CategoryID, &t.Type, &t.Amount, &t.Description, &t.Date, &t.CreatedAt,
			&t.CategoryName, &t.CategoryEmoji); err != nil {
			return nil, err
		}
		txs = append(txs, t)
	}
	return txs, nil
}

func (r *FinanceRepository) GetTransaction(id, userID int64) (*model.FinanceTransaction, error) {
	var t model.FinanceTransaction
	query := `SELECT t.id, t.user_id, t.category_id, t.type, t.amount, t.description, t.date, t.created_at,
		COALESCE(c.name,'') as category_name, COALESCE(c.emoji,'') as category_emoji
		FROM finance_transactions t LEFT JOIN finance_categories c ON c.id = t.category_id
		WHERE t.id=$1 AND t.user_id=$2`
	err := r.db.QueryRow(query, id, userID).Scan(&t.ID, &t.UserID, &t.CategoryID, &t.Type, &t.Amount, &t.Description, &t.Date, &t.CreatedAt,
		&t.CategoryName, &t.CategoryEmoji)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrFinanceTransactionNotFound
		}
		return nil, err
	}
	return &t, nil
}

func (r *FinanceRepository) UpdateTransaction(tx *model.FinanceTransaction) error {
	query := `UPDATE finance_transactions SET category_id=$2, type=$3, amount=$4, description=$5, date=$6
		WHERE id=$1 AND user_id=$7`
	result, err := r.db.Exec(query, tx.ID, tx.CategoryID, tx.Type, tx.Amount, tx.Description, tx.Date, tx.UserID)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrFinanceTransactionNotFound
	}
	return nil
}

func (r *FinanceRepository) DeleteTransaction(id, userID int64) error {
	result, err := r.db.Exec(`DELETE FROM finance_transactions WHERE id=$1 AND user_id=$2`, id, userID)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrFinanceTransactionNotFound
	}
	return nil
}

// --- Summary & Analytics ---

func (r *FinanceRepository) GetSummary(userID int64, month, year int) (*model.FinanceSummary, error) {
	summary := &model.FinanceSummary{}

	// First day of selected month and last day of selected month
	firstDay := time.Date(year, time.Month(month), 1, 0, 0, 0, 0, time.UTC)
	lastDay := firstDay.AddDate(0, 1, -1)

	// Carried over: balance of all transactions BEFORE the selected month
	err := r.db.QueryRow(`SELECT COALESCE(SUM(CASE WHEN type='income' THEN amount ELSE -amount END), 0)
		FROM finance_transactions WHERE user_id=$1 AND date < $2`,
		userID, firstDay).Scan(&summary.CarriedOver)
	if err != nil {
		return nil, err
	}

	// Total income & expense for the month
	err = r.db.QueryRow(`SELECT COALESCE(SUM(CASE WHEN type='income' THEN amount ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN type='expense' THEN amount ELSE 0 END),0)
		FROM finance_transactions WHERE user_id=$1 AND EXTRACT(MONTH FROM date)=$2 AND EXTRACT(YEAR FROM date)=$3`,
		userID, month, year).Scan(&summary.TotalIncome, &summary.TotalExpense)
	if err != nil {
		return nil, err
	}

	// Cumulative balance: all transactions up to end of selected month
	err = r.db.QueryRow(`SELECT COALESCE(SUM(CASE WHEN type='income' THEN amount ELSE -amount END), 0)
		FROM finance_transactions WHERE user_id=$1 AND date <= $2`,
		userID, lastDay).Scan(&summary.Balance)
	if err != nil {
		return nil, err
	}

	// By category
	rows, err := r.db.Query(`SELECT c.id, c.name, c.emoji, t.type, SUM(t.amount) as amount
		FROM finance_transactions t JOIN finance_categories c ON c.id=t.category_id
		WHERE t.user_id=$1 AND EXTRACT(MONTH FROM t.date)=$2 AND EXTRACT(YEAR FROM t.date)=$3
		GROUP BY c.id, c.name, c.emoji, t.type ORDER BY amount DESC`, userID, month, year)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	for rows.Next() {
		var cs model.CategorySummary
		if err := rows.Scan(&cs.CategoryID, &cs.CategoryName, &cs.CategoryEmoji, &cs.Type, &cs.Amount); err != nil {
			return nil, err
		}
		total := summary.TotalExpense
		if cs.Type == "income" {
			total = summary.TotalIncome
		}
		if total > 0 {
			cs.Percentage = cs.Amount / total * 100
		}
		summary.ByCategory = append(summary.ByCategory, cs)
	}
	if summary.ByCategory == nil {
		summary.ByCategory = []model.CategorySummary{}
	}

	// Daily expenses
	dailyRows, err := r.db.Query(`SELECT date::text, SUM(amount) as amount
		FROM finance_transactions WHERE user_id=$1 AND type='expense' AND EXTRACT(MONTH FROM date)=$2 AND EXTRACT(YEAR FROM date)=$3
		GROUP BY date ORDER BY date`, userID, month, year)
	if err != nil {
		return nil, err
	}
	defer dailyRows.Close()

	for dailyRows.Next() {
		var d model.DailySummary
		if err := dailyRows.Scan(&d.Date, &d.Amount); err != nil {
			return nil, err
		}
		summary.Daily = append(summary.Daily, d)
	}
	if summary.Daily == nil {
		summary.Daily = []model.DailySummary{}
	}

	return summary, nil
}

func (r *FinanceRepository) GetAnalytics(userID int64, months int) (*model.FinanceAnalytics, error) {
	analytics := &model.FinanceAnalytics{}

	// Monthly trend
	rows, err := r.db.Query(`SELECT TO_CHAR(date, 'YYYY-MM') as month,
		COALESCE(SUM(CASE WHEN type='income' THEN amount ELSE 0 END),0) as income,
		COALESCE(SUM(CASE WHEN type='expense' THEN amount ELSE 0 END),0) as expense
		FROM finance_transactions WHERE user_id=$1 AND date >= (CURRENT_DATE - ($2 || ' months')::interval)
		GROUP BY TO_CHAR(date, 'YYYY-MM') ORDER BY month`, userID, months)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	for rows.Next() {
		var mt model.MonthlyTrend
		if err := rows.Scan(&mt.Month, &mt.Income, &mt.Expense); err != nil {
			return nil, err
		}
		analytics.MonthlyTrend = append(analytics.MonthlyTrend, mt)
	}
	if analytics.MonthlyTrend == nil {
		analytics.MonthlyTrend = []model.MonthlyTrend{}
	}

	// Avg daily expense for current month
	now := time.Now()
	var totalExpense float64
	var dayCount int
	r.db.QueryRow(`SELECT COALESCE(SUM(amount),0), COUNT(DISTINCT date)
		FROM finance_transactions WHERE user_id=$1 AND type='expense'
		AND EXTRACT(MONTH FROM date)=$2 AND EXTRACT(YEAR FROM date)=$3`,
		userID, int(now.Month()), now.Year()).Scan(&totalExpense, &dayCount)
	if dayCount > 0 {
		analytics.AvgDailyExpense = totalExpense / float64(dayCount)
	}

	// Comparison with previous month
	prevMonth := now.AddDate(0, -1, 0)
	var currentMonthExp, prevMonthExp float64
	r.db.QueryRow(`SELECT COALESCE(SUM(amount),0) FROM finance_transactions WHERE user_id=$1 AND type='expense'
		AND EXTRACT(MONTH FROM date)=$2 AND EXTRACT(YEAR FROM date)=$3`,
		userID, int(now.Month()), now.Year()).Scan(&currentMonthExp)
	r.db.QueryRow(`SELECT COALESCE(SUM(amount),0) FROM finance_transactions WHERE user_id=$1 AND type='expense'
		AND EXTRACT(MONTH FROM date)=$2 AND EXTRACT(YEAR FROM date)=$3`,
		userID, int(prevMonth.Month()), prevMonth.Year()).Scan(&prevMonthExp)

	analytics.ComparisonPrevMonth = model.Comparison{
		Current:  currentMonthExp,
		Previous: prevMonthExp,
	}
	if prevMonthExp > 0 {
		analytics.ComparisonPrevMonth.DiffPercent = (currentMonthExp - prevMonthExp) / prevMonthExp * 100
	}

	return analytics, nil
}

func (r *FinanceRepository) HasCategories(userID int64) (bool, error) {
	var count int
	err := r.db.Get(&count, `SELECT COUNT(*) FROM finance_categories WHERE user_id=$1`, userID)
	return count > 0, err
}