package releaseidentity

import (
	"context"
	"errors"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
)

func TestDeriveUsesModuleDeclarationAndPhysicalLayout(t *testing.T) {
	tests := []struct {
		name       string
		subdir     string
		modulePath string
		version    string
		wantTag    string
		wantNote   string
	}{
		{name: "root v1", subdir: ".", modulePath: "example.com/root", version: "v1.2.3", wantTag: "v1.2.3", wantNote: "docs/releases/v1.2.3.md"},
		{name: "local main module", subdir: ".", modulePath: "example", version: "v1.2.3", wantTag: "v1.2.3", wantNote: "docs/releases/v1.2.3.md"},
		{name: "local major module", subdir: "apps/local/v2", modulePath: "example/v2", version: "v2.3.4", wantTag: "apps/local/v2.3.4", wantNote: "apps/local/v2/docs/releases/v2.3.4.md"},
		{name: "nested", subdir: "integrations/check", modulePath: "example.com/check", version: "v1.2.3", wantTag: "integrations/check/v1.2.3", wantNote: "integrations/check/docs/releases/v1.2.3.md"},
		{name: "root major path", subdir: ".", modulePath: "example.com/root/v2", version: "v2.3.4", wantTag: "v2.3.4", wantNote: "docs/releases/v2.3.4.md"},
		{name: "root physical major directory", subdir: "v2", modulePath: "example.com/root/v2", version: "v2.3.4", wantTag: "v2.3.4", wantNote: "v2/docs/releases/v2.3.4.md"},
		{name: "physical major directory", subdir: "integrations/check/v2", modulePath: "example.com/check/v2", version: "v2.3.4", wantTag: "integrations/check/v2.3.4", wantNote: "integrations/check/v2/docs/releases/v2.3.4.md"},
		{name: "logical major without physical directory", subdir: "integrations/check", modulePath: "example.com/check/v2", version: "v2.3.4", wantTag: "integrations/check/v2.3.4", wantNote: "integrations/check/docs/releases/v2.3.4.md"},
		{name: "ordinary directory named v2", subdir: "integrations/v2", modulePath: "example.com/check", version: "v1.2.3", wantTag: "integrations/v2/v1.2.3", wantNote: "integrations/v2/docs/releases/v1.2.3.md"},
		{name: "gopkg special major", subdir: "integrations/example.v2", modulePath: "gopkg.in/example.v2", version: "v2.3.4", wantTag: "integrations/example.v2/v2.3.4", wantNote: "integrations/example.v2/docs/releases/v2.3.4.md"},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			selection := Selection{RepositoryDir: "/repo", ModuleDir: filepath.Join("/repo", filepath.FromSlash(tt.subdir)), ModuleSubdir: tt.subdir}
			if tt.subdir == "." {
				selection.ModuleDir = "/repo"
			}
			got, err := Derive(selection, []byte("module "+tt.modulePath+"\n"), tt.version)
			if err != nil {
				t.Fatal(err)
			}
			if got.Tag != tt.wantTag || got.NotePath != tt.wantNote {
				t.Fatalf("identity tag/note = %q, %q; want %q, %q", got.Tag, got.NotePath, tt.wantTag, tt.wantNote)
			}
		})
	}
}

func TestDeriveRejectsInvalidModuleAndVersionIdentity(t *testing.T) {
	selection := Selection{RepositoryDir: "/repo", ModuleDir: "/repo", ModuleSubdir: "."}
	for _, tt := range []struct {
		name, declaration, version string
	}{
		{name: "missing module directive", declaration: "go 1.26\n", version: "v1.2.3"},
		{name: "malformed module path", declaration: "module example.com/../bad\n", version: "v1.2.3"},
		{name: "incompatible major", declaration: "module example.com/service/v2\n", version: "v1.2.3"},
		{name: "incompatible local major", declaration: "module example/v2\n", version: "v1.2.3"},
		{name: "invalid local module path", declaration: "module example/../bad\n", version: "v1.2.3"},
		{name: "unstable version", declaration: "module example.com/service\n", version: "v1.2.3-rc.1"},
	} {
		t.Run(tt.name, func(t *testing.T) {
			if _, err := Derive(selection, []byte(tt.declaration), tt.version); err == nil {
				t.Fatal("Derive() succeeded for invalid identity")
			}
		})
	}
}

func TestResolveSelectionNormalizesAndRejectsEscape(t *testing.T) {
	repository := t.TempDir()
	moduleDir := filepath.Join(repository, "integrations", "one")
	if err := os.MkdirAll(moduleDir, 0o755); err != nil {
		t.Fatal(err)
	}
	selection, err := ResolveSelection(repository, "integrations/one/../one")
	if err != nil {
		t.Fatal(err)
	}
	if selection.ModuleSubdir != "integrations/one" || selection.ModuleDir != moduleDir {
		t.Fatalf("normalized selection = %#v", selection)
	}
	root, err := ResolveSelection(repository, "")
	if err != nil || root.ModuleSubdir != "." || root.ModuleDir != repository {
		t.Fatalf("default root selection = %#v, error = %v", root, err)
	}
	if _, err := ResolveSelection(repository, "../outside"); err == nil {
		t.Fatal("ResolveSelection() accepted a path outside the repository")
	}
	if _, err := ResolveSelection(repository, moduleDir); err == nil {
		t.Fatal("ResolveSelection() accepted an absolute module path")
	}
	outside := t.TempDir()
	link := filepath.Join(repository, "linked")
	if err := os.Symlink(outside, link); err != nil {
		t.Fatal(err)
	}
	if _, err := ResolveSelection(repository, "linked"); err == nil {
		t.Fatal("ResolveSelection() accepted a symlink that resolves outside the repository")
	}
}

func TestCommittedAndWorkingTreeDeclarationsUseTheirOwnSources(t *testing.T) {
	repository := t.TempDir()
	gitIdentityRun(t, repository, "init", "-q")
	gitIdentityRun(t, repository, "config", "user.name", "ReleaseKit test")
	gitIdentityRun(t, repository, "config", "user.email", "releasekit@example.invalid")
	moduleDir := filepath.Join(repository, "nested", "mod")
	if err := os.MkdirAll(moduleDir, 0o755); err != nil {
		t.Fatal(err)
	}
	declaration := filepath.Join(moduleDir, "go.mod")
	if err := os.WriteFile(declaration, []byte("module example.com/committed\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	gitIdentityRun(t, repository, "add", ".")
	gitIdentityRun(t, repository, "commit", "-qm", "add module")
	commit := strings.TrimSpace(gitIdentityOutput(t, repository, "rev-parse", "HEAD"))
	if err := os.WriteFile(declaration, []byte("module example.com/working\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	committed, err := FromCommitted(context.Background(), repository, "nested/mod", "v1.2.3", commit)
	if err != nil {
		t.Fatal(err)
	}
	working, err := FromWorkingTree(context.Background(), repository, "nested/mod", "v1.2.3")
	if err != nil {
		t.Fatal(err)
	}
	if committed.ModulePath != "example.com/committed" || committed.Tag != "nested/mod/v1.2.3" {
		t.Fatalf("committed identity = %#v", committed)
	}
	if working.ModulePath != "example.com/working" || working.Tag != "nested/mod/v1.2.3" {
		t.Fatalf("working identity = %#v", working)
	}
}

func TestCommittedIdentityFollowsCapturedDeclarationAndDirectoryLinks(t *testing.T) {
	repository := t.TempDir()
	gitIdentityRun(t, repository, "init", "-q")
	gitIdentityRun(t, repository, "config", "user.name", "ReleaseKit test")
	gitIdentityRun(t, repository, "config", "user.email", "releasekit@example.invalid")
	moduleDir := filepath.Join(repository, "nested")
	if err := os.Mkdir(moduleDir, 0o755); err != nil {
		t.Fatal(err)
	}
	declaration := filepath.Join(repository, "module.txt")
	if err := os.WriteFile(declaration, []byte("module example.com/committed\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink("../module.txt", filepath.Join(moduleDir, "go.mod")); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink("nested", filepath.Join(repository, "selected")); err != nil {
		t.Fatal(err)
	}
	gitIdentityRun(t, repository, "add", ".")
	gitIdentityRun(t, repository, "commit", "-qm", "Add linked declaration")
	commit := strings.TrimSpace(gitIdentityOutput(t, repository, "rev-parse", "HEAD"))
	if err := os.WriteFile(declaration, []byte("module example.com/working\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	committed, err := FromCommitted(t.Context(), repository, "selected", "v1.2.3", commit)
	if err != nil || committed.ModulePath != "example.com/committed" || committed.ModuleDir != moduleDir || committed.Tag != "nested/v1.2.3" {
		t.Fatalf("committed linked identity = %#v, error = %v", committed, err)
	}
	working, err := FromWorkingTree(t.Context(), repository, "selected", "v1.2.3")
	if err != nil || working.ModulePath != "example.com/working" || working.ModuleDir != moduleDir {
		t.Fatalf("working linked identity = %#v, error = %v", working, err)
	}
	ctx, cancel := context.WithCancel(t.Context())
	cancel()
	if _, err := FromCommitted(ctx, repository, "selected", "v1.2.3", commit); !errors.Is(err, context.Canceled) {
		t.Fatalf("canceled committed identity error = %v", err)
	}
}

func TestCommittedIdentityPreservesReferenceFailures(t *testing.T) {
	for _, mode := range []string{"cycle", "outside", "missing", "unavailable blob"} {
		t.Run(mode, func(t *testing.T) {
			repository := t.TempDir()
			gitIdentityRun(t, repository, "init", "-q")
			gitIdentityRun(t, repository, "config", "user.name", "ReleaseKit test")
			gitIdentityRun(t, repository, "config", "user.email", "releasekit@example.invalid")
			target, wantCause := "go.mod", "symlink-cycle"
			switch mode {
			case "outside":
				target, wantCause = "../module.txt", "outside-checkout"
			case "missing":
				target, wantCause = "missing.mod", "missing"
			case "unavailable blob":
				target, wantCause = "module.txt", "read selected module declaration"
				if err := os.WriteFile(filepath.Join(repository, target), []byte("module example.com/linked\n"), 0o644); err != nil {
					t.Fatal(err)
				}
			}
			if err := os.Symlink(target, filepath.Join(repository, "go.mod")); err != nil {
				t.Fatal(err)
			}
			gitIdentityRun(t, repository, "add", ".")
			gitIdentityRun(t, repository, "commit", "-qm", "Add reference fixture")
			commit := strings.TrimSpace(gitIdentityOutput(t, repository, "rev-parse", "HEAD"))
			if mode == "unavailable blob" {
				object := strings.TrimSpace(gitIdentityOutput(t, repository, "rev-parse", "HEAD:module.txt"))
				if err := os.Remove(filepath.Join(repository, ".git", "objects", object[:2], object[2:])); err != nil {
					t.Fatal(err)
				}
			}
			identity, err := FromCommitted(t.Context(), repository, ".", "v1.2.3", commit)
			if err == nil || !strings.Contains(err.Error(), wantCause) || identity.RepositoryDir != repository || identity.ModuleDir != repository {
				t.Fatalf("identity = %#v, error = %v; want %s", identity, err, wantCause)
			}
		})
	}
}

func TestSelectedNestedModuleDoesNotRequireRootDeclaration(t *testing.T) {
	repository := t.TempDir()
	moduleDir := filepath.Join(repository, "nested")
	if err := os.MkdirAll(moduleDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(moduleDir, "go.mod"), []byte("module example.com/nested\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	identity, err := FromWorkingTree(context.Background(), repository, "nested", "v1.2.3")
	if err != nil || identity.ModulePath != "example.com/nested" {
		t.Fatalf("nested identity = %#v, error = %v", identity, err)
	}
	if _, err := FromWorkingTree(context.Background(), repository, ".", "v1.2.3"); err == nil {
		t.Fatal("root selection silently fell back to a nested module declaration")
	}
}

func TestReadersPreserveCancellation(t *testing.T) {
	repository := t.TempDir()
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	if _, err := FromWorkingTree(ctx, repository, ".", "v1.2.3"); err == nil || !strings.Contains(err.Error(), context.Canceled.Error()) {
		t.Fatalf("working-tree error = %v, want cancellation", err)
	}
}

func gitIdentityRun(t *testing.T, dir string, args ...string) {
	t.Helper()
	command := exec.Command("git", args...)
	command.Dir = dir
	if output, err := command.CombinedOutput(); err != nil {
		t.Fatalf("git %v: %v\n%s", args, err, output)
	}
}

func gitIdentityOutput(t *testing.T, dir string, args ...string) string {
	t.Helper()
	command := exec.Command("git", args...)
	command.Dir = dir
	output, err := command.Output()
	if err != nil {
		t.Fatalf("git %v: %v", args, err)
	}
	return string(output)
}