package main

import (
	"fmt"
	"log"
	"net/http"
	"sync"
	"time"

	"git.makerforce.io/photos/photos/internal/httphelpers"
	lib "git.makerforce.io/photos/photos/pkg/bucket"
	"github.com/davidbyttow/govips/pkg/vips"
)

var client *lib.Client

type resizeOperation struct {
	input         []byte
	previewOption lib.PreviewOption
	output        []byte
	err           error
	took          time.Duration
}

const maxAspectRatio = 6

func main() {
	// Setup bucket client
	var err error
	client, err = lib.NewClientFromEnv()
	if err != nil {
		panic(err)
	}

	// Setup vips
	vips.Startup(nil)
	defer vips.Shutdown()

	server := &http.Server{
		Addr:         ":8003",
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 10 * time.Second,
	}
	http.HandleFunc("/update", update)
	err = server.ListenAndServe()
	if err != nil {
		panic(err)
	}
}

func update(w http.ResponseWriter, req *http.Request) {
	if req.Method != http.MethodPost {
		err := fmt.Errorf("%w: %v", httphelpers.ErrorMethodNotAllowed, req.Method)
		httphelpers.ErrorResponse(w, err)
		return
	}

	bucket := lib.Bucket(req.FormValue("bucket"))
	photo := lib.Photo(req.FormValue("photo"))
	/*
		bucketMetadata, err := client.GetBucketMetadata(bucket)
		previewOptions := bucketMetadata.PreviewOptions
	*/
	previewOptions := lib.DefaultPreviewOptions()

	original, err := client.GetPhoto(bucket, photo)
	if err != nil {
		httphelpers.ErrorResponse(w, err)
		return
	}

	resizes := make([]resizeOperation, len(previewOptions))
	for i := range resizes {
		resizes[i] = resizeOperation{
			input:         original,
			previewOption: previewOptions[i],
		}
	}

	var wg sync.WaitGroup

	for i := range resizes {
		op := &resizes[i]
		wg.Add(1)
		// TODO: timeouts
		go func() {
			start := time.Now()
			log.Printf("Resizing photo %s at h%dq%d", photo, op.previewOption.Height, op.previewOption.Quality)
			output, err := resize(
				op.input,
				op.previewOption.Height,
				toVipsImageType(op.previewOption.Format),
				op.previewOption.Quality,
			)
			op.output = output
			op.err = err
			end := time.Now()
			op.took = end.Sub(start)
			wg.Done()
		}()
	}

	wg.Wait()
	// Check for errors
	for _, op := range resizes {
		if op.err != nil {
			httphelpers.ErrorResponse(w, err)
			return
		}
	}

	// Save
	for i := range resizes {
		op := &resizes[i]
		wg.Add(1)
		go func() {
			preview := photo.GetPreview(op.previewOption)
			err := client.PutPreview(bucket, preview, op.output)
			log.Printf("Uploaded photo %s at h%dq%d: %v", photo, op.previewOption.Height, op.previewOption.Quality, err)
			op.err = err
			wg.Done()
		}()
	}

	wg.Wait()
	// Check for errors
	for _, op := range resizes {
		if op.err != nil {
			httphelpers.ErrorResponse(w, err)
			return
		}
	}

	timings := make([]time.Duration, 0)
	for _, op := range resizes {
		timings = append(timings, op.took)
	}
	w.Header().Add("X-Debug-Resize-Timings", fmt.Sprintf("%v", timings))
}

func resize(buf []byte, height int, format vips.ImageType, quality int) ([]byte, error) {
	i, err := vips.NewImageFromBuffer(buf)
	if err != nil {
		return nil, err
	}
	defer i.Close()

	scale := float64(height) / float64(i.Height())
	err = i.Resize(scale)
	if err != nil {
		return nil, err
	}
	outBuf, _, err := i.Export(vips.ExportParams{
		Format:  format,
		Quality: quality,
	})
	return outBuf, err
}

func toVipsImageType(format lib.PhotoFormat) vips.ImageType {
	if format == lib.PhotoFormatWEBP {
		return vips.ImageTypeWEBP
	}
	if format == lib.PhotoFormatJPEG {
		return vips.ImageTypeJPEG
	}
	return vips.ImageTypeUnknown
}