package releasekit

import (
	"context"
	"io"

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

// Target identifies one explicit Go operating-system and architecture pair.
type Target struct {
	OS   string // Go operating system name, such as "linux".
	Arch string // Go architecture name, such as "amd64".
}

// BuildSpec selects the application package, output name, and target pairs.
type BuildSpec struct {
	MainPackage string   // Go package path to build, such as "./cmd/app".
	BinaryName  string   // filename component used in output artifacts.
	Targets     []Target // selected target pairs; duplicates are removed in order.
}

// BuildRequest contains the source and output settings for Build.
type BuildRequest struct {
	RepositoryDir string    // source repository whose current HEAD is recorded.
	Version       string    // stable vMAJOR.MINOR.PATCH value injected at link time.
	Spec          BuildSpec // application package, artifact name, and targets.
	OutputDir     string    // output location; empty selects <repository>/dist.
	Output        io.Writer // optional build progress destination.
}

// BuildArtifact identifies one generated binary and its SHA-256 digest.
type BuildArtifact struct {
	Path     string // absolute path to the generated binary.
	Filename string // generated filename.
	Target   Target // Go target used for this artifact.
	SHA256   string // lowercase hexadecimal digest of the complete file.
}

// BuildResult describes the source and artifacts reached by Build.
type BuildResult struct {
	RepositoryDir   string // absolute source repository path.
	CandidateCommit string // Git HEAD observed when the build started.
	// SourceVerified reports clean source and the same HEAD observed before and
	// after a completed build. It is required for binary delivery, not an attestation.
	SourceVerified bool
	Version        string          // requested injected version.
	MainPackage    string          // Go package path built.
	BinaryName     string          // artifact name prefix.
	OutputDir      string          // resolved output directory.
	Targets        []Target        // normalized target pairs.
	Artifacts      []BuildArtifact // completed output files, including partial success.
	Compiler       string          // output of the selected local Go toolchain's version command.
}

// Build compiles the selected targets with Version injected through buildinfo.
// It uses the prepared local Go environment, regenerates selected output files while preserving unrelated files,
// and verifies the version command on the native host before succeeding. An
// empty target set records source identity without running the Go toolchain.
// Errors return partial build facts in the result.
func Build(ctx context.Context, request BuildRequest) (BuildResult, error) {
	targets := make([]internalbuild.Target, 0, len(request.Spec.Targets))
	for _, target := range request.Spec.Targets {
		targets = append(targets, internalbuild.Target{OS: target.OS, Arch: target.Arch})
	}
	result, err := internalbuild.Build(ctx, internalbuild.Request{
		RepositoryDir: request.RepositoryDir,
		Version:       request.Version,
		Spec: internalbuild.Spec{
			MainPackage: request.Spec.MainPackage,
			BinaryName:  request.Spec.BinaryName,
			Targets:     targets,
		},
		OutputDir: request.OutputDir,
		Output:    request.Output,
	})
	public := BuildResult{
		RepositoryDir:   result.RepositoryDir,
		CandidateCommit: result.CandidateCommit,
		SourceVerified:  result.SourceVerified,
		Version:         result.Version,
		MainPackage:     result.MainPackage,
		BinaryName:      result.BinaryName,
		OutputDir:       result.OutputDir,
		Compiler:        result.Compiler,
		Targets:         make([]Target, 0, len(result.Targets)),
		Artifacts:       make([]BuildArtifact, 0, len(result.Artifacts)),
	}
	for _, target := range result.Targets {
		public.Targets = append(public.Targets, Target{OS: target.OS, Arch: target.Arch})
	}
	for _, artifact := range result.Artifacts {
		public.Artifacts = append(public.Artifacts, BuildArtifact{
			Path:     artifact.Path,
			Filename: artifact.Filename,
			Target:   Target{OS: artifact.Target.OS, Arch: artifact.Target.Arch},
			SHA256:   artifact.SHA256,
		})
	}
	return public, err
}