package bookings

import (
	"context"
	"encoding/json"
	"errors"
	"strconv"
	"strings"
	"time"

	"crussell/db"
)

// ErrPastClosing is returned by checkClosingHours when the booking's end time
// exceeds the working hours closing time for that day.
var ErrPastClosing = errors.New("booking extends beyond closing hours")

// checkClosingHours verifies that a booking end time (in Europe/London wall-clock
// time) does not exceed the closing time stored as "HH:MM" in the working_hours
// table. Returns ErrPastClosing if the booking runs past close, or a generic
// error if closeStr cannot be parsed.
// getClosingTimeForDate resolves the closing time for a booking on a given
// date/weekday. It first checks for a pending default_hours_scheduled_changes
// whose effective_date <= the booking date; if found, the staged hours' closing
// time for that weekday is returned. Otherwise falls back to the current
// working_hours table. Returns the closing time as "HH:MM" (or "HH:MM:SS").
func getClosingTimeForDate(ctx context.Context, q db.Querier, weekday int, bookingDate time.Time) (string, error) {
	// Check for a pending staged change that applies to this date
	type stagedHour struct {
		Weekday   int    `json:"weekday"`
		StartTime string `json:"startTime"`
		EndTime   string `json:"endTime"`
		IsOpen    bool   `json:"isOpen"`
	}
	var hoursJSON string
	err := q.QueryRow(ctx, `
		SELECT hours::text
		FROM default_hours_scheduled_changes
		WHERE effective_date <= $1::date
		  AND applied_at IS NULL
		  AND cancelled_at IS NULL
		ORDER BY effective_date DESC
		LIMIT 1
	`, bookingDate.Format("2006-01-02")).Scan(&hoursJSON)
	if err == nil && hoursJSON != "" {
		var staged []stagedHour
		if json.Unmarshal([]byte(hoursJSON), &staged) == nil {
			for _, h := range staged {
				if h.Weekday == weekday && h.IsOpen {
					return h.EndTime, nil
				}
			}
		}
		// Staged change found but weekday is closed — return "00:00" so the
		// caller can reject the booking (the day would be closed under the
		// staged schedule).
		return "00:00", nil
	}

	// Fall back to current working_hours table
	var closeStr string
	if err := q.QueryRow(ctx, `SELECT end_time::text FROM working_hours WHERE weekday = $1`, weekday).Scan(&closeStr); err != nil {
		return "", err
	}
	return closeStr, nil
}

func checkClosingHours(localEnd time.Time, closeStr string) error {
	parts := strings.Split(closeStr, ":")
	if len(parts) < 2 {
		return errors.New("invalid closing time format")
	}
	closeHour, err := strconv.Atoi(parts[0])
	if err != nil {
		return errors.New("invalid closing time format")
	}
	closeMin, err := strconv.Atoi(parts[1])
	if err != nil {
		return errors.New("invalid closing time format")
	}
	if localEnd.Hour() > closeHour || (localEnd.Hour() == closeHour && localEnd.Minute() > closeMin) {
		return ErrPastClosing
	}
	return nil
}