// Command index-pack ingests one pack stream from stdin and writes .pack/.idx/.rev.
package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"

	"codeberg.org/lindenii/furgit/format/pack/ingest"
	"codeberg.org/lindenii/furgit/objectid"
	"codeberg.org/lindenii/furgit/objectstore"
	"codeberg.org/lindenii/furgit/repository"
)

func main() {
	repoPath := flag.String("r", "", "path to git dir (.git or bare repo root)")
	destinationPath := flag.String("destination", "", "path to destination objects/pack directory")
	objectFormat := flag.String("object-format", "", "object format (sha1 or sha256)")
	fixThin := flag.Bool("fix-thin", false, "fix thin packs using repository object store")
	writeRev := flag.Bool("rev-index", true, "write reverse index (.rev)")

	flag.Parse()

	if *destinationPath == "" {
		log.Fatal("must provide -destination <objects/pack>")
	}

	err := run(*repoPath, *destinationPath, *objectFormat, *fixThin, *writeRev)
	if err != nil {
		log.Fatalf("run: %v", err)
	}
}

func run(repoPath, destinationPath, objectFormat string, fixThin, writeRev bool) error {
	var (
		algo objectid.Algorithm
		base objectstore.Store
		repo *repository.Repository
	)

	if repoPath != "" {
		repoRoot, err := os.OpenRoot(repoPath)
		if err != nil {
			return fmt.Errorf("open repo root: %w", err)
		}

		defer func() { _ = repoRoot.Close() }()

		repo, err = repository.Open(repoRoot)
		if err != nil {
			return fmt.Errorf("open repository: %w", err)
		}

		defer func() { _ = repo.Close() }()
	}

	algo, err := resolveAlgorithm(repo, objectFormat)
	if err != nil {
		return err
	}

	if fixThin {
		if repo == nil {
			return fmt.Errorf("fix-thin requires -r <repo>")
		}

		if repo.Algorithm() != algo {
			return fmt.Errorf("algorithm mismatch: repo=%s flag=%s", repo.Algorithm(), algo)
		}

		base = repo.Objects()
	}

	absDestination, err := filepath.Abs(destinationPath)
	if err != nil {
		return fmt.Errorf("absolute destination path: %w", err)
	}

	destinationRoot, err := os.OpenRoot(absDestination)
	if err != nil {
		return fmt.Errorf("open destination root: %w", err)
	}

	defer func() { _ = destinationRoot.Close() }()

	result, err := ingest.Ingest(os.Stdin, destinationRoot, algo, fixThin, writeRev, base)
	if err != nil {
		return err
	}

	_, _ = fmt.Fprintf(os.Stdout, "pack\t%s\n", result.PackHash.String())

	return nil
}

func resolveAlgorithm(repo *repository.Repository, objectFormat string) (objectid.Algorithm, error) {
	if objectFormat != "" {
		algo, ok := objectid.ParseAlgorithm(objectFormat)
		if !ok {
			return objectid.AlgorithmUnknown, fmt.Errorf("invalid object format %q", objectFormat)
		}

		return algo, nil
	}

	if repo != nil {
		return repo.Algorithm(), nil
	}

	return objectid.AlgorithmSHA1, nil
}