package delivery

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	internalbuild "gitea.maximumdirect.net/eric/ReleaseKit/internal/build"
	"gitea.maximumdirect.net/eric/ReleaseKit/internal/gitea"
)

func declaredBuildAssets(result internalbuild.Result) ([]gitea.ExpectedAsset, error) {
	if len(result.Targets) == 0 {
		if len(result.Artifacts) != 0 {
			return nil, fmt.Errorf("source-only build result contains artifacts")
		}
		return nil, nil
	}
	if len(result.Artifacts) != len(result.Targets) {
		return nil, fmt.Errorf("build result must contain one artifact for each selected target")
	}
	wantByTarget := make(map[string]string, len(result.Targets))
	for _, target := range result.Targets {
		if target.OS == "" || target.Arch == "" || strings.ContainsAny(target.OS+target.Arch, "/\\\r\n") {
			return nil, fmt.Errorf("build result contains an invalid target")
		}
		key := target.OS + "/" + target.Arch
		if _, exists := wantByTarget[key]; exists {
			return nil, fmt.Errorf("build result repeats target %q", key)
		}
		name := result.BinaryName + "-" + result.Version + "-" + target.OS + "-" + target.Arch
		if target.OS == "windows" {
			name += ".exe"
		}
		wantByTarget[key] = name
	}
	assets := make([]gitea.ExpectedAsset, 0, len(result.Artifacts)+1)
	seenTargets := make(map[string]bool, len(result.Artifacts))
	for _, artifact := range result.Artifacts {
		key := artifact.Target.OS + "/" + artifact.Target.Arch
		wantName, ok := wantByTarget[key]
		if !ok || seenTargets[key] || artifact.Filename != wantName {
			return nil, fmt.Errorf("build artifact %q does not match a selected target and its declared name", artifact.Filename)
		}
		seenTargets[key] = true
		if filepath.Base(artifact.Path) != artifact.Filename {
			return nil, fmt.Errorf("build artifact path %q does not end with filename %q", artifact.Path, artifact.Filename)
		}
		info, err := os.Stat(artifact.Path)
		if err != nil {
			return nil, fmt.Errorf("inspect build artifact %q: %w", artifact.Filename, err)
		}
		if !info.Mode().IsRegular() {
			return nil, fmt.Errorf("build artifact %q is not a regular file", artifact.Filename)
		}
		file, err := os.Open(artifact.Path)
		if err != nil {
			return nil, fmt.Errorf("open build artifact %q: %w", artifact.Filename, err)
		}
		hash := sha256.New()
		_, copyErr := io.Copy(hash, file)
		closeErr := file.Close()
		if copyErr != nil {
			return nil, fmt.Errorf("hash build artifact %q: %w", artifact.Filename, copyErr)
		}
		if closeErr != nil {
			return nil, fmt.Errorf("close build artifact %q: %w", artifact.Filename, closeErr)
		}
		if artifact.SHA256 != hex.EncodeToString(hash.Sum(nil)) {
			return nil, fmt.Errorf("build artifact %q does not match its declared SHA-256 digest", artifact.Filename)
		}
		assets = append(assets, gitea.ExpectedAsset{
			Filename: artifact.Filename,
			SHA256:   artifact.SHA256,
			Size:     info.Size(),
			Path:     artifact.Path,
		})
	}
	manifest, err := gitea.BuildManifest(assets)
	if err != nil {
		return nil, fmt.Errorf("build checksum manifest: %w", err)
	}
	if manifest.Filename != "" {
		assets = append(assets, manifest)
	}
	return assets, nil
}