package diyanetprovider

import (
	"context"
	"errors"
	"fmt"
	"time"

	"prayertimes/pkg/prayer"
)

type APIProvider interface {
	Get(ctx context.Context, locationID string) ([]prayer.Times, error)
	GetByCoords(ctx context.Context, coords prayer.Coordinates) ([]prayer.Times, error)
}

type FallbackProvider interface {
	GetByCoords(ctx context.Context, coords prayer.Coordinates) ([]prayer.Times, error)
}

type Provider struct {
	api      APIProvider
	fallback FallbackProvider
	timeout  time.Duration
}

func New(api APIProvider, fallback FallbackProvider) Provider {
	return Provider{
		api:      api,
		fallback: fallback,
		timeout:  2 * time.Second,
	}
}

var ErrEmptyTimes = errors.New("diyanet did not return any prayer times")

func (p Provider) Get(ctx context.Context, locationID string) ([]prayer.Times, error) {
	ctxWithTimeout, cancel := context.WithTimeout(ctx, p.timeout)
	defer cancel()

	times, err := p.api.Get(ctxWithTimeout, locationID)
	if err != nil {
		return nil, fmt.Errorf("failed to get prayer times from api provider: %w", err)
	}
	if len(times) == 0 {
		return nil, ErrEmptyTimes
	}

	return times, nil
}

func (p Provider) GetByCoords(ctx context.Context, coords prayer.Coordinates) ([]prayer.Times, error) {
	ctxWithTimeout, cancel := context.WithTimeout(ctx, p.timeout)
	defer cancel()

	times, err := p.api.GetByCoords(ctxWithTimeout, coords)
	if err == nil && len(times) > 0 {
		return times, nil
	}

	times, err = p.fallback.GetByCoords(ctx, coords)
	if err != nil {
		return nil, fmt.Errorf("failed to get prayer times from fallback provider: %w", err)
	}

	if len(times) == 0 {
		return nil, fmt.Errorf("fallback provider did not return any prayer times")
	}

	return times, nil
}