package reforger_utils

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"slices"
	"strings"
)

var Debug = false

func DoAssetsRequest(addonID, version string) (AssetsReply, error) {
	url := "https://api-ar-workshop.bistudio.com/workshop-api/api/v3.0/s2s/assets/download-list"
	body := `{"assets":{"` + addonID + `":"` + version + `"}}`
	req, err := http.NewRequest("POST", url, strings.NewReader(body))
	if err != nil {
		return AssetsReply{}, err
	}

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return AssetsReply{}, err
	}
	defer res.Body.Close()

	if res.StatusCode != 200 {
		// print entire body
		body, _ := io.ReadAll(res.Body)
		fmt.Println(string(body))
		return AssetsReply{}, fmt.Errorf("bad status: %s", res.Status)
	}

	// Process response
	decoder := json.NewDecoder(res.Body)
	var assetsReply AssetsReply
	if err := decoder.Decode(&assetsReply); err != nil {
		panic(err)
	}

	return assetsReply, nil
}

func GetManifest(manifestUrl string) (Manifest, error) {
	url := "https://ar-gcp-cdn.bistudio.com/manifest/" + manifestUrl
	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return Manifest{}, err
	}

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return Manifest{}, err
	}
	defer res.Body.Close()

	if res.StatusCode != 200 {
		return Manifest{}, fmt.Errorf("bad status: %s", res.Status)
	}

	// Decode the JSON response
	var manifest Manifest
	if err := json.NewDecoder(res.Body).Decode(&manifest); err != nil {
		panic(err)
	}

	return manifest, nil
}

func Download(manifest Manifest, downloadDir string, filen string) ([]byte, error) {

	if Debug {
		// create the directory if it doesn't exist
		if err := os.MkdirAll(downloadDir+"/fragments/"+filen, os.ModePerm); err != nil {
			return nil, err
		}
	}

	// download remainder
	downloaded := 0
	remContent := make([]byte, 0)
	currentRem := 0
	if manifest.Remainder.Size > 0 {
		url := transformShaToURL(manifest.Remainder.Sha512, manifest.Remainder.Size)
		content, err := getContent(url)
		if err != nil {
			return nil, err
		}
		remContent = content
		downloaded += len(content)

		if Debug {
			// save remainder to file in the fragments/ directory, prefix with gap
			if err := os.WriteFile(filepath.Join(downloadDir, "fragments", filen, fmt.Sprintf("%d.%s.%d.bytes", manifest.Remainder.Offsets[0], manifest.Remainder.Sha512, manifest.Remainder.Size)), remContent, os.ModePerm); err != nil {
				return nil, err
			}
		}
	}

	trackFrag := make([]Frag, 0)

	// start downloading chunks
	//currentOffset := 0
	ret := make([]byte, manifest.Size)
	totalMB := float32(manifest.Size) / 1024.0 / 1024.0
	for _, fragment := range manifest.Fragments {
		url := transformShaToURL(fragment.Sha512, fragment.Size)
		content, err := getContent(url)
		if err != nil {
			return nil, err
		}
		downloaded += len(content) * len(fragment.Offsets)
		for _, offset := range fragment.Offsets {
			trackFrag = append(trackFrag, Frag{Offset: offset, Size: len(content)})
			copy(ret[offset:offset+len(content)], content)
		}

		if Debug {
			// save fragment to file in the fragments/ directory
			if err := os.WriteFile(filepath.Join(downloadDir, "fragments", filen, fmt.Sprintf("%d.%s.%d.bytes", fragment.Offsets[0], fragment.Sha512, fragment.Size)), content, os.ModePerm); err != nil {
				return nil, err
			}
		}

		percent := float32(downloaded) / float32(manifest.Size) * 100.0
		downedMB := float32(downloaded) / 1024.0 / 1024.0
		fmt.Printf("\r\033[32mDownloaded\033[0m %fMB/%fMB (\033[36m%.2f%%\033[0m) of \033[33m%s\033[0m", downedMB, totalMB, percent, filen)
	}

	// sort trackFrag by Offset
	slices.SortFunc(trackFrag, func(a, b Frag) int {
		return a.Offset - b.Offset
	})

	// check for gaps in trackFrag and fill with remainder content
	curPos := 0
	for _, frag := range trackFrag {
		if frag.Offset > curPos {
			// gap detected
			gapSize := frag.Offset - curPos
			if currentRem+gapSize > len(remContent) {
				panic("not enough remainder content to fill gap")
			}
			copy(ret[curPos:curPos+gapSize], remContent[currentRem:currentRem+gapSize])
			remContent = remContent[gapSize:]
		}
		curPos = frag.Offset + frag.Size
	}

	// Append rest of remainder content
	copy(ret[curPos:], remContent)
	fmt.Println()

	return ret, nil
}

func getContent(url string) ([]byte, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("bad status: %s", resp.Status)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	return body, nil
}

func transformShaToURL(sha512s string, size int) string {
	return "https://ar-gcp-cdn.bistudio.com/fragment/" + sha512s[0:4] + "/" + sha512s[4:8] + "/" + sha512s[8:] + "/" + fmt.Sprintf("%d", size)
}