// Copyright 2021-2022 EMQ Technologies Co., Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"bytes"
	"fmt"
	"image"
	"image/gif"
	"image/jpeg"
	"image/png"

	"github.com/nfnt/resize"

	"github.com/lf-edge/ekuiper/pkg/api"
)

type imageResize struct{}

func (f *imageResize) Validate(args []interface{}) error {
	if len(args) < 3 {
		return fmt.Errorf("The resize function must have at least 3 parameters, but got %d", len(args))
	}
	return nil
}

func (f *imageResize) IsAggregate() bool {
	return false
}

func (f *imageResize) Exec(args []interface{}, ctx api.FunctionContext) (interface{}, bool) {
	arg, ok := args[0].([]byte)
	if !ok {
		return fmt.Errorf("arg[0] is not a bytea, got %v", args[0]), false
	}
	width, ok := args[1].(int)
	if !ok || 0 > width {
		return fmt.Errorf("arg[1] is not a bigint, got %v", args[1]), false
	}
	height, ok := args[2].(int)
	if !ok || 0 > height {
		return fmt.Errorf("arg[2] is not a bigint, got %v", args[2]), false
	}
	isRaw := false
	if len(args) > 3 {
		isRaw, ok = args[3].(bool)
		if !ok {
			return fmt.Errorf("arg[3] is not a bool, got %v", args[3]), false
		}
	}
	ctx.GetLogger().Debugf("resize: %d %d, output raw %v", width, height, isRaw)

	img, format, err := image.Decode(bytes.NewReader(arg))
	if nil != err {
		return fmt.Errorf("image decode error:%v", err), false
	}

	img = resize.Resize(uint(width), uint(height), img, resize.Bilinear)
	if isRaw {
		bounds := img.Bounds()
		dx, dy := bounds.Dx(), bounds.Dy()
		bb := make([]byte, width*height*3)
		for y := 0; y < dy; y++ {
			for x := 0; x < dx; x++ {
				col := img.At(x, y)
				r, g, b, _ := col.RGBA()
				bb[(y*dx+x)*3+0] = byte(float64(r) / 255.0)
				bb[(y*dx+x)*3+1] = byte(float64(g) / 255.0)
				bb[(y*dx+x)*3+2] = byte(float64(b) / 255.0)
			}
		}
		return bb, true
	} else {
		var b []byte
		buf := bytes.NewBuffer(b)
		switch format {
		case "png":
			err = png.Encode(buf, img)
		case "jpeg":
			err = jpeg.Encode(buf, img, nil)
		case "gif":
			err = gif.Encode(buf, img, nil)
		default:
			return fmt.Errorf("%s image type is not currently supported", format), false
		}
		if nil != err {
			return fmt.Errorf("image encode error:%v", err), false
		}
		return buf.Bytes(), true
	}
}

var ResizeWithChan imageResize