package topdata

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"slices"
	"strings"

	"gitea.westgate.pw/ShadowsOverWestgate/sow-tools/internal/erf"
	"gitea.westgate.pw/ShadowsOverWestgate/sow-tools/internal/project"
)

const (
	PackageHAKResRef   = "sow_top"
	PackageHAKFileName = PackageHAKResRef + ".hak"
	PackageTLKFileName = defaultTLKName
)

func BuildPackage(p *project.Project, progress func(string)) (PackageResult, error) {
	if progress == nil {
		progress = func(string) {}
	}
	nativeResult, err := BuildNative(p, progress)
	if err != nil {
		return PackageResult{}, err
	}
	return packageBuiltTopData(p, nativeResult, progress)
}

func packageBuiltTopData(p *project.Project, nativeResult BuildResult, progress func(string)) (PackageResult, error) {
	if progress == nil {
		progress = func(string) {}
	}
	buildDir := p.BuildDir()
	outputHAK := filepath.Join(buildDir, PackageHAKFileName)
	outputTLK := filepath.Join(buildDir, PackageTLKFileName)

	progress("Packaging compiled topdata resources into sow_top.hak...")
	resources, assetFiles, err := collectTopPackageResources(p, nativeResult.Output2DADir)
	if err != nil {
		return PackageResult{}, err
	}
	if err := writeHAK(outputHAK, resources); err != nil {
		return PackageResult{}, err
	}

	progress("Preparing compiled TLK release output...")
	sourceTLK, err := resolveCompiledTLKPath(nativeResult.OutputTLKDir)
	if err != nil {
		return PackageResult{}, err
	}
	if err := copyFile(outputTLK, sourceTLK); err != nil {
		return PackageResult{}, err
	}

	return PackageResult{
		Mode:          nativeResult.Mode,
		Output2DADir:  nativeResult.Output2DADir,
		OutputTLKDir:  nativeResult.OutputTLKDir,
		OutputHAKPath: outputHAK,
		OutputTLKPath: outputTLK,
		Files2DA:      nativeResult.Files2DA,
		FilesTLK:      nativeResult.FilesTLK,
		HAKResources:  len(resources),
		AssetFiles:    assetFiles,
	}, nil
}

func collectTopPackageResources(p *project.Project, compiled2DADir string) ([]erf.Resource, int, error) {
	resourceByKey := map[string]erf.Resource{}

	entries, err := os.ReadDir(compiled2DADir)
	if err != nil {
		return nil, 0, fmt.Errorf("read compiled 2da output dir: %w", err)
	}
	for _, entry := range entries {
		if entry.IsDir() || !strings.EqualFold(filepath.Ext(entry.Name()), ".2da") {
			continue
		}
		path := filepath.Join(compiled2DADir, entry.Name())
		resource, err := topPackageResourceFromPath(path)
		if err != nil {
			return nil, 0, err
		}
		resourceByKey[topPackageResourceKey(resource)] = resource
	}

	assetFiles := 0
	assetsDir := filepath.Join(p.TopDataSourceDir(), "assets")
	info, err := os.Stat(assetsDir)
	if err == nil && info.IsDir() {
		err = filepath.WalkDir(assetsDir, func(path string, d os.DirEntry, walkErr error) error {
			if walkErr != nil {
				return walkErr
			}
			if d.IsDir() {
				return nil
			}
			if strings.HasPrefix(filepath.Base(path), ".") {
				return nil
			}
			resource, err := topPackageResourceFromPath(path)
			if err != nil {
				return err
			}
			key := topPackageResourceKey(resource)
			if _, ok := resourceByKey[key]; ok {
				return fmt.Errorf("topdata asset %s collides with generated top package resource %s", path, key)
			}
			resourceByKey[key] = resource
			assetFiles++
			return nil
		})
		if err != nil {
			return nil, 0, err
		}
	} else if err != nil && !os.IsNotExist(err) {
		return nil, 0, fmt.Errorf("stat topdata assets dir: %w", err)
	}

	keys := make([]string, 0, len(resourceByKey))
	for key := range resourceByKey {
		keys = append(keys, key)
	}
	slices.Sort(keys)

	resources := make([]erf.Resource, 0, len(keys))
	for _, key := range keys {
		resources = append(resources, resourceByKey[key])
	}
	return resources, assetFiles, nil
}

func topPackageResourceFromPath(path string) (erf.Resource, error) {
	extension := strings.TrimPrefix(strings.ToLower(filepath.Ext(path)), ".")
	resourceType, ok := erf.ResourceTypeForExtension(extension)
	if !ok {
		return erf.Resource{}, fmt.Errorf("unsupported top package resource extension %q", filepath.Ext(path))
	}
	info, err := os.Stat(path)
	if err != nil {
		return erf.Resource{}, fmt.Errorf("stat %s: %w", path, err)
	}
	return erf.Resource{
		Name:       strings.ToLower(strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))),
		Type:       resourceType,
		SourcePath: path,
		Size:       info.Size(),
	}, nil
}

func topPackageResourceKey(resource erf.Resource) string {
	extension, ok := erf.ExtensionForResourceType(resource.Type)
	if !ok {
		return strings.ToLower(resource.Name)
	}
	return strings.ToLower(resource.Name) + "." + strings.TrimPrefix(strings.ToLower(extension), ".")
}

func writeHAK(path string, resources []erf.Resource) error {
	output, err := os.Create(path)
	if err != nil {
		return fmt.Errorf("create top package hak: %w", err)
	}
	defer output.Close()
	if err := erf.Write(output, erf.New("HAK ", resources)); err != nil {
		return fmt.Errorf("write top package hak: %w", err)
	}
	return nil
}

func resolveCompiledTLKPath(outputDir string) (string, error) {
	entries, err := os.ReadDir(outputDir)
	if err != nil {
		return "", fmt.Errorf("read compiled tlk output dir: %w", err)
	}
	var tlkFiles []string
	for _, entry := range entries {
		if entry.IsDir() || !strings.EqualFold(filepath.Ext(entry.Name()), ".tlk") {
			continue
		}
		tlkFiles = append(tlkFiles, filepath.Join(outputDir, entry.Name()))
	}
	if len(tlkFiles) != 1 {
		return "", fmt.Errorf("expected exactly 1 compiled tlk output, found %d", len(tlkFiles))
	}
	return tlkFiles[0], nil
}

func copyFile(dst, src string) error {
	input, err := os.Open(src)
	if err != nil {
		return fmt.Errorf("open %s: %w", src, err)
	}
	defer input.Close()

	output, err := os.Create(dst)
	if err != nil {
		return fmt.Errorf("create %s: %w", dst, err)
	}
	defer output.Close()

	if _, err := io.Copy(output, input); err != nil {
		return fmt.Errorf("copy %s to %s: %w", src, dst, err)
	}
	return nil
}