// Package scheduling defines the platform-wide scheduling and timeslot seam:
// wire shapes, DTOs, domain events, and client interfaces for booking services,
// appointments, and capacity-based timeslots.
//
// Like platform/inventory and platform/order, this package depends only on the
// stdlib and shared platform types (money, uid, event).
package scheduling

import (
	"encoding/json"
	"errors"
	"time"
)

var (
	// ErrSlotUnavailable is returned when a requested slot has no remaining capacity.
	ErrSlotUnavailable = errors.New("scheduling: requested timeslot is not available")
	// ErrHoldExpired is returned when attempting to confirm or extend an expired hold.
	ErrHoldExpired = errors.New("scheduling: hold has expired")
	// ErrBookingNotFound is returned when the specified booking is not found.
	ErrBookingNotFound = errors.New("scheduling: booking not found")
	// ErrResourceNotFound is returned when the specified resource or schedule is not found.
	ErrResourceNotFound = errors.New("scheduling: resource not found")
	// ErrOutsideWorkingHours is returned when a hold/booking window does not
	// lie inside the resource's configured working hours (weekly rules or a
	// date override). Guards the hold/direct-booking/reschedule appliers so
	// API clients cannot reserve capacity outside bookable windows.
	ErrOutsideWorkingHours = errors.New("scheduling: window is outside working hours")
)

// Slot represents a discrete bookable window of time.
type Slot struct {
	StartTime time.Time `json:"start_time"`
	EndTime   time.Time `json:"end_time"`
	Capacity  int       `json:"capacity"`
	Remaining int       `json:"remaining"`
}

// ResourceConfig defines a bookable resource (staff member, room, bay, equipment).
type ResourceConfig struct {
	ID             string        `json:"id"`
	Name           string        `json:"name"`
	LocationID     string        `json:"location_id,omitempty"`
	Timezone       string        `json:"timezone"`
	Capacity       int           `json:"capacity"`         // max concurrent bookings per slot (default 1)
	SlotDuration   time.Duration `json:"slot_duration"`    // standard duration if not overridden
	BufferBefore   time.Duration `json:"buffer_before"`    // buffer time before appointments
	BufferAfter    time.Duration `json:"buffer_after"`     // buffer time after appointments
	MinLeadTime    time.Duration `json:"min_lead_time"`    // minimum advance notice required
	MaxAdvanceTime time.Duration `json:"max_advance_time"` // maximum booking window into the future
}

// WorkingHours defines recurring weekly schedule rules (e.g. Mon-Fri 09:00-17:00).
type WorkingHours struct {
	DayOfWeek int    `json:"day_of_week"` // 0 = Sunday, 1 = Monday, ..., 6 = Saturday
	StartTime string `json:"start_time"`  // "09:00" (HH:MM)
	EndTime   string `json:"end_time"`    // "17:00" (HH:MM)
}

// ScheduleOverride defines a specific blackout (holiday, sick leave) or custom opening.
type ScheduleOverride struct {
	Date        string `json:"date"`                   // "2026-09-01" (YYYY-MM-DD)
	IsClosed    bool   `json:"is_closed"`              // true for complete closure / blackout
	CustomStart string `json:"custom_start,omitempty"` // custom opening if not closed
	CustomEnd   string `json:"custom_end,omitempty"`
	Reason      string `json:"reason,omitempty"`
}

// HoldRequest is the payload to request a temporary TTL reservation on a slot.
type HoldRequest struct {
	ResourceID string    `json:"resource_id"`
	StartTime  time.Time `json:"start_time"`
	EndTime    time.Time `json:"end_time"`
	Quantity   int       `json:"quantity"` // number of capacity units (default 1)
	CartID     string    `json:"cart_id,omitempty"`
	TTLSeconds int       `json:"ttl_seconds,omitempty"` // hold duration in seconds (default 900 = 15m)
}

// HoldResult is returned when a slot hold is successfully placed.
type HoldResult struct {
	HoldID     string    `json:"hold_id"`
	ResourceID string    `json:"resource_id"`
	StartTime  time.Time `json:"start_time"`
	EndTime    time.Time `json:"end_time"`
	Quantity   int       `json:"quantity"`
	ExpiresAt  time.Time `json:"expires_at"`
}

// BookingStatus represents the lifecycle state of a booking.
type BookingStatus string

const (
	BookingStatusConfirmed BookingStatus = "confirmed"
	BookingStatusCancelled BookingStatus = "cancelled"
	BookingStatusCompleted BookingStatus = "completed"
	BookingStatusNoShow    BookingStatus = "no_show"
)

// BookingDetails holds a confirmed booking record.
type BookingDetails struct {
	BookingID     string        `json:"booking_id"`
	HoldID        string        `json:"hold_id,omitempty"`
	OrderID       string        `json:"order_id,omitempty"`
	ResourceID    string        `json:"resource_id"`
	ResourceName  string        `json:"resource_name,omitempty"`
	SKU           string        `json:"sku,omitempty"`
	ServiceName   string        `json:"service_name,omitempty"`
	StartTime     time.Time     `json:"start_time"`
	EndTime       time.Time     `json:"end_time"`
	Quantity      int           `json:"quantity"`
	CustomerEmail string        `json:"customer_email,omitempty"`
	CustomerName  string        `json:"customer_name,omitempty"`
	CustomerPhone string        `json:"customer_phone,omitempty"`
	Notes         string        `json:"notes,omitempty"`
	Status        BookingStatus `json:"status"`
	CreatedAt     time.Time     `json:"created_at"`
}

// BookingConfirmedEvent is the payload for event.SchedulingBookingConfirmed.
type BookingConfirmedEvent struct {
	BookingID     string    `json:"booking_id"`
	OrderID       string    `json:"order_id"`
	ResourceID    string    `json:"resource_id"`
	SKU           string    `json:"sku,omitempty"`
	StartTime     time.Time `json:"start_time"`
	EndTime       time.Time `json:"end_time"`
	Quantity      int       `json:"quantity"`
	CustomerEmail string    `json:"customer_email,omitempty"`
	CustomerName  string    `json:"customer_name,omitempty"`
}

// Encode serializes the event payload.
func (e BookingConfirmedEvent) Encode() ([]byte, error) { return json.Marshal(e) }

// DecodeBookingConfirmed parses the event payload.
func DecodeBookingConfirmed(raw []byte) (BookingConfirmedEvent, error) {
	var e BookingConfirmedEvent
	err := json.Unmarshal(raw, &e)
	return e, err
}

// BookingCancelledEvent is the payload for event.SchedulingBookingCancelled.
type BookingCancelledEvent struct {
	BookingID string `json:"booking_id"`
	OrderID   string `json:"order_id,omitempty"`
	Reason    string `json:"reason,omitempty"`
}

// Encode serializes the event payload.
func (e BookingCancelledEvent) Encode() ([]byte, error) { return json.Marshal(e) }

// DecodeBookingCancelled parses the event payload.
func DecodeBookingCancelled(raw []byte) (BookingCancelledEvent, error) {
	var e BookingCancelledEvent
	err := json.Unmarshal(raw, &e)
	return e, err
}