// Command xtsync vendors the pinned xcb-proto sources. An explicit -source
// directory supports offline refreshes; its provenance is retained in manifest.
package main

import (
	"archive/tar"
	"bytes"
	"compress/gzip"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"time"
)

const upstream = "https://gitlab.freedesktop.org/xorg/proto/xcbproto"
const tag = "xcb-proto-1.17.0"

var files = []string{"xproto.xml", "bigreq.xml", "ge.xml", "xc_misc.xml", "composite.xml", "xfixes.xml", "res.xml", "render.xml", "shape.xml", "xcb.xsd", "COPYING"}

type entry struct {
	Path   string `json:"path"`
	SHA256 string `json:"sha256"`
}
type manifest struct {
	Upstream string  `json:"upstream"`
	Tag      string  `json:"tag"`
	Source   string  `json:"source"`
	Files    []entry `json:"files"`
}

func main() {
	source := flag.String("source", "", "local source directory (COPYING must be included)")
	flag.Parse()
	if err := syncFiles(*source); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}
func syncFiles(source string) error {
	data := make(map[string][]byte)
	provenance := source
	if source != "" {
		for _, name := range files {
			b, err := os.ReadFile(filepath.Join(source, name))
			if err != nil {
				return err
			}
			data[name] = b
		}
	} else {
		provenance = upstream + "/-/archive/" + tag + "/xcbproto-" + tag + ".tar.gz"
		client := http.Client{Timeout: 30 * time.Second}
		resp, err := client.Get(provenance)
		if err != nil {
			return err
		}
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return fmt.Errorf("download: %s", resp.Status)
		}
		gz, err := gzip.NewReader(io.LimitReader(resp.Body, 16<<20))
		if err != nil {
			return err
		}
		defer gz.Close()
		tr := tar.NewReader(gz)
		for {
			h, err := tr.Next()
			if err == io.EOF {
				break
			}
			if err != nil {
				return err
			}
			for _, name := range files {
				if h.Name == "xcbproto-"+tag+"/src/"+name || name == "COPYING" && h.Name == "xcbproto-"+tag+"/COPYING" {
					b, err := io.ReadAll(io.LimitReader(tr, 4<<20))
					if err != nil {
						return err
					}
					data[name] = b
				}
			}
		}
	}
	m := manifest{Upstream: upstream, Tag: tag, Source: provenance}
	for _, name := range files {
		if len(data[name]) == 0 {
			return fmt.Errorf("missing source %s", name)
		}
	}
	for _, name := range files {
		dest := filepath.Join("spec", "xml", name)
		if name == "xcb.xsd" {
			dest = "spec/xcb.xsd"
		}
		if name == "COPYING" {
			dest = "LICENSES/xcb-proto-COPYING"
		}
		if err := os.MkdirAll(filepath.Dir(dest), 0755); err != nil {
			return err
		}
		if err := os.WriteFile(dest, data[name], 0644); err != nil {
			return err
		}
		sum := sha256.Sum256(data[name])
		m.Files = append(m.Files, entry{filepath.ToSlash(dest), hex.EncodeToString(sum[:])})
	}
	b, err := json.MarshalIndent(m, "", "  ")
	if err != nil {
		return err
	}
	b = append(b, '\n')
	// Keep refresh deterministic, including when invoked repeatedly from CI.
	old, _ := os.ReadFile("spec/manifest.json")
	if bytes.Equal(old, b) {
		return nil
	}
	return os.WriteFile("spec/manifest.json", b, 0644)
}