package main

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"time"
)

type FileMeta struct {
	Size    int64
	Mode    os.FileMode
	ModTime time.Time
	Symlink string
}

type Manifest struct {
	Files map[string]FileMeta
}

type syncStats struct {
	files   int
	dirs    int
	skipped int
	errors  int
}

func initialSync(hostDir, dataDir string, stack *GitignoreStack, dryRun bool) (*Manifest, error) {
	manifest := &Manifest{Files: make(map[string]FileMeta)}
	stats := &syncStats{}
	start := time.Now()

	logInfo("initial sync: scanning %s ...", hostDir)

	err := filepath.Walk(hostDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			stats.errors++
			logErrorf("walk %s: %v", path, err)
			return nil
		}

		relPath, err := filepath.Rel(hostDir, path)
		if err != nil {
			return err
		}

		if relPath == "." {
			return nil
		}

		if isGitDir(relPath) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		if info.IsDir() && hasGitignore(path) {
			stack.Push(path)
		}

		if stack.IsIgnored(relPath) {
			stats.skipped++
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		if info.IsDir() {
			stats.dirs++
		} else {
			stats.files++
		}

		if stats.files%1000 == 0 && stats.files > 0 {
			fmt.Fprintf(os.Stderr, "\r  synced %d files, %d dirs ...", stats.files, stats.dirs)
		}

		destPath := filepath.Join(dataDir, relPath)

		linkTarget := ""
		if info.Mode()&os.ModeSymlink != 0 {
			linkTarget, err = os.Readlink(path)
			if err != nil {
				stats.errors++
				logErrorf("readlink %s: %v", relPath, err)
				return nil
			}
		}

		meta := FileMeta{
			Size:    info.Size(),
			Mode:    info.Mode(),
			ModTime: info.ModTime(),
			Symlink: linkTarget,
		}
		manifest.Files[relPath] = meta

		if dryRun {
			return nil
		}

		if info.IsDir() {
			if err := os.MkdirAll(destPath, info.Mode()); err != nil {
				stats.errors++
				logErrorf("mkdir %s: %v", relPath, err)
			}
			return nil
		}

		if err := os.MkdirAll(filepath.Dir(destPath), 0755); err != nil {
			stats.errors++
			logErrorf("mkdir %s: %v", filepath.Dir(relPath), err)
			return nil
		}

		if linkTarget != "" {
			if err := os.Symlink(linkTarget, destPath); err != nil {
				stats.errors++
				logErrorf("symlink %s: %v", relPath, err)
			}
			return nil
		}

		if err := copyFileWithRetry(path, destPath, info.Mode()); err != nil {
			stats.errors++
			logErrorf("copy %s: %v", relPath, err)
		}
		return nil
	})

	elapsed := time.Since(start)
	fmt.Fprintf(os.Stderr, "\r")
	logInfo("initial sync: done in %s — %d files, %d dirs, %d skipped, %d errors",
		elapsed.Round(time.Millisecond), stats.files, stats.dirs, stats.skipped, stats.errors)

	return manifest, err
}

func copyFile(src, dst string, mode os.FileMode) error {
	srcFile, err := os.Open(src)
	if err != nil {
		return err
	}
	defer srcFile.Close()

	dstFile, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode)
	if err != nil {
		return err
	}
	defer dstFile.Close()

	_, err = io.Copy(dstFile, srcFile)
	return err
}