package candidate

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

	"gitea.maximumdirect.net/eric/ReleaseKit/internal/validation"
)

const testVersion = "v1.2.3"

func TestValidStableVersion(t *testing.T) {
	for _, version := range []string{
		"v0.0.0",
		"v1.2.3",
		"v123456789012345678901234567890.0.9",
	} {
		if !validStableVersion(version) {
			t.Errorf("validStableVersion(%q) = false", version)
		}
	}
	for _, version := range []string{
		"",
		"1.2.3",
		"V1.2.3",
		"v01.2.3",
		"v1.02.3",
		"v1.2.03",
		"v1.2",
		"v1.2.3-alpha",
		"v1..3",
		"v+1.2.3",
	} {
		if validStableVersion(version) {
			t.Errorf("validStableVersion(%q) = true", version)
		}
	}
}

func TestCheckCapturesCandidateAndCallsAdditionalChecksOnce(t *testing.T) {
	repository := newRepository(t, "# Example Product v1.2.3\n\nRelease note.\n")
	calls := 0
	var seen Candidate
	candidate, err := Check(context.Background(), Request{
		RepositoryDir: repository,
		Product:       "Example Product",
		Version:       testVersion,
		AdditionalChecks: func(_ context.Context, captured Candidate) error {
			calls++
			seen = captured
			return nil
		},
	})
	if err != nil {
		t.Fatal(err)
	}
	commit := gitOutputForTest(t, repository, "rev-parse", "HEAD")
	if calls != 1 {
		t.Fatalf("validation callback called %d times, want 1", calls)
	}
	if seen != candidate {
		t.Fatalf("callback candidate = %#v, returned candidate = %#v", seen, candidate)
	}
	if candidate.RepositoryDir != repository || candidate.Commit != commit || candidate.Version != testVersion {
		t.Fatalf("Check() candidate = %#v", candidate)
	}
	if tags := gitOutputForTest(t, repository, "tag", "--list"); tags != "" {
		t.Fatalf("Check created local tags: %q", tags)
	}
	if refs := gitOutputForTest(t, repository, "for-each-ref", "--format=%(refname)", "refs/remotes"); refs != "" {
		t.Fatalf("Check created remote-tracking refs: %q", refs)
	}
}

func TestCheckRunsDefaultOfflineGoValidation(t *testing.T) {
	repository := newRepository(t, "# Example Product v1.2.3\n\nRelease note.\n")
	var output bytes.Buffer
	_, err := Check(context.Background(), Request{
		RepositoryDir: repository,
		Product:       "Example Product",
		Version:       testVersion,
		Output:        &output,
	})
	if err != nil {
		t.Fatalf("Check() with default validation: %v\n%s", err, output.String())
	}
}

func TestDefaultValidationDoesNotInheritGOFLAGSRunFilter(t *testing.T) {
	repository := newRepository(t, "# Example Product v1.2.3\n\nRelease note.\n")
	writeTestFile(t, repository, "failure_test.go", "package candidate\nimport \"testing\"\nfunc TestExpectedFailure(t *testing.T) { t.Fatal(\"expected fixture failure\") }\n")
	gitRun(t, repository, "add", "failure_test.go")
	gitRun(t, repository, "commit", "-m", "add failing validation fixture")

	for _, source := range []string{"process environment", "Go environment file"} {
		t.Run(source, func(t *testing.T) {
			unsetCandidateEnv(t, "GOFLAGS", "GOOS", "GOARCH")
			goEnv := filepath.Join(t.TempDir(), "go-env")
			if source == "Go environment file" {
				if err := os.WriteFile(goEnv, []byte("GOFLAGS=-run=^$\nGOOS=windows\nGOARCH=arm64\n"), 0o600); err != nil {
					t.Fatal(err)
				}
			} else {
				if err := os.WriteFile(goEnv, nil, 0o600); err != nil {
					t.Fatal(err)
				}
				t.Setenv("GOFLAGS", "-run=^$")
				t.Setenv("GOOS", "windows")
				t.Setenv("GOARCH", "arm64")
			}
			t.Setenv("GOENV", goEnv)
			var output bytes.Buffer
			_, err := Check(context.Background(), Request{
				RepositoryDir: repository,
				Product:       "Example Product",
				Version:       testVersion,
				Output:        &output,
			})
			if err == nil || !strings.Contains(output.String(), "TestExpectedFailure") {
				t.Fatalf("Check() error = %v, output = %q; wanted the failing standard test to run", err, output.String())
			}
			var failure *validation.Failure
			if !errors.As(err, &failure) || failure.Check != validation.GoTest {
				t.Fatalf("Check() error = %v; want a go-test validation failure", err)
			}
			var exitErr *exec.ExitError
			if !errors.As(err, &exitErr) {
				t.Fatalf("Check() error = %v; want the Go process exit error preserved", err)
			}
		})
	}
}

func unsetCandidateEnv(t *testing.T, keys ...string) {
	t.Helper()
	for _, key := range keys {
		value, exists := os.LookupEnv(key)
		if err := os.Unsetenv(key); err != nil {
			t.Fatal(err)
		}
		t.Cleanup(func() {
			if exists {
				_ = os.Setenv(key, value)
			} else {
				_ = os.Unsetenv(key)
			}
		})
	}
}

func TestCheckRejectsInvalidVersionsBeforeGitAccess(t *testing.T) {
	for _, version := range []string{"v01.2.3", "v1.2.3-alpha", "1.2.3"} {
		t.Run(version, func(t *testing.T) {
			_, err := Check(context.Background(), Request{Version: version})
			if !errors.Is(err, ErrInvalidVersion) {
				t.Fatalf("Check() error = %v, want ErrInvalidVersion", err)
			}
		})
	}
}

func TestCheckRequiresMatchingCommittedNote(t *testing.T) {
	tests := []struct {
		name string
		note string
	}{
		{name: "missing note"},
		{name: "wrong product", note: "# Other Product v1.2.3\n"},
		{name: "wrong version", note: "# Example Product v1.2.4\n"},
		{name: "embedded product text", note: "# Example Products v1.2.3\n"},
		{name: "not a level one heading", note: "## Example Product v1.2.3\n"},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			repository := newRepository(t, test.note)
			called := false
			_, err := Check(context.Background(), Request{
				RepositoryDir: repository,
				Product:       "Example Product",
				Version:       testVersion,
				AdditionalChecks: func(context.Context, Candidate) error {
					called = true
					return nil
				},
			})
			if err == nil {
				t.Fatal("Check() succeeded with an invalid committed note")
			}
			if called {
				t.Fatal("validation ran before the committed note passed")
			}
		})
	}
}

func TestCheckRejectsDirtyTrackedAndUntrackedState(t *testing.T) {
	for _, test := range []struct {
		name  string
		path  string
		value string
	}{
		{name: "tracked", path: "tracked.txt", value: "changed\n"},
		{name: "untracked", path: "new file.txt", value: "untracked\n"},
	} {
		t.Run(test.name, func(t *testing.T) {
			repository := newRepository(t, "# Example Product v1.2.3\n")
			if err := os.WriteFile(filepath.Join(repository, test.path), []byte(test.value), 0o600); err != nil {
				t.Fatal(err)
			}
			_, err := Check(context.Background(), validRequest(repository))
			if err == nil || !strings.Contains(err.Error(), "must be clean") {
				t.Fatalf("Check() error = %v, want dirty state error", err)
			}
		})
	}
}

func TestCheckRequiresMainBranchAndUnusedTag(t *testing.T) {
	t.Run("detached HEAD", func(t *testing.T) {
		repository := newRepository(t, "# Example Product v1.2.3\n")
		gitRun(t, repository, "checkout", "--detach", "HEAD")
		_, err := Check(context.Background(), validRequest(repository))
		if err == nil || !strings.Contains(err.Error(), "must be on main") {
			t.Fatalf("Check() error = %v, want branch error", err)
		}
	})
	t.Run("existing local tag", func(t *testing.T) {
		repository := newRepository(t, "# Example Product v1.2.3\n")
		gitRun(t, repository, "tag", testVersion)
		_, err := Check(context.Background(), validRequest(repository))
		if err == nil || !strings.Contains(err.Error(), "already exists") {
			t.Fatalf("Check() error = %v, want existing-tag error", err)
		}
	})
}

func TestCheckStopsOnAdditionalCheckFailure(t *testing.T) {
	repository := newRepository(t, "# Example Product v1.2.3\n")
	want := errors.New("selected check failed")
	calls := 0
	_, err := Check(context.Background(), Request{
		RepositoryDir: repository,
		Product:       "Example Product",
		Version:       testVersion,
		AdditionalChecks: func(context.Context, Candidate) error {
			calls++
			return want
		},
	})
	if !errors.Is(err, want) {
		t.Fatalf("Check() error = %v, want wrapped callback error", err)
	}
	if calls != 1 {
		t.Fatalf("validation callback called %d times, want 1", calls)
	}
}

func TestCheckRechecksHeadAndWorktreeAfterCallback(t *testing.T) {
	tests := []struct {
		name     string
		validate func(*testing.T, string)
		want     string
	}{
		{
			name: "HEAD changes",
			validate: func(t *testing.T, repository string) {
				t.Helper()
				if err := os.WriteFile(filepath.Join(repository, "later.txt"), []byte("later\n"), 0o600); err != nil {
					t.Fatal(err)
				}
				gitRun(t, repository, "add", "later.txt")
				gitRun(t, repository, "-c", "commit.gpgsign=false", "commit", "-m", "advance HEAD")
			},
			want: "HEAD changed from",
		},
		{
			name: "worktree changes",
			validate: func(t *testing.T, repository string) {
				t.Helper()
				if err := os.WriteFile(filepath.Join(repository, "later.txt"), []byte("later\n"), 0o600); err != nil {
					t.Fatal(err)
				}
			},
			want: "worktree or index changed",
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			repository := newRepository(t, "# Example Product v1.2.3\n")
			_, err := Check(context.Background(), Request{
				RepositoryDir: repository,
				Product:       "Example Product",
				Version:       testVersion,
				AdditionalChecks: func(context.Context, Candidate) error {
					test.validate(t, repository)
					return nil
				},
			})
			if err == nil || !strings.Contains(err.Error(), test.want) {
				t.Fatalf("Check() error = %v, want text %q", err, test.want)
			}
		})
	}
}

func TestCheckRechecksLocalTagAfterCallback(t *testing.T) {
	repository := newRepository(t, "# Example Product v1.2.3\n")
	_, err := Check(context.Background(), Request{
		RepositoryDir: repository,
		Product:       "Example Product",
		Version:       testVersion,
		AdditionalChecks: func(context.Context, Candidate) error {
			gitRun(t, repository, "tag", testVersion)
			return nil
		},
	})
	if err == nil || !strings.Contains(err.Error(), "appeared during validation") {
		t.Fatalf("Check() error = %v, want tag recheck error", err)
	}
}

func validRequest(repository string) Request {
	return Request{RepositoryDir: repository, Product: "Example Product", Version: testVersion, AdditionalChecks: func(context.Context, Candidate) error { return nil }}
}

func newRepository(t *testing.T, note string) string {
	t.Helper()
	repository := filepath.Join(t.TempDir(), "repository with spaces")
	if err := os.Mkdir(repository, 0o700); err != nil {
		t.Fatal(err)
	}
	gitRun(t, repository, "init", "--initial-branch=main")
	gitRun(t, repository, "config", "user.name", "ReleaseKit Test")
	gitRun(t, repository, "config", "user.email", "releasekit@example.test")
	gitRun(t, repository, "config", "commit.gpgsign", "false")
	writeTestFile(t, repository, "go.mod", "module example.com/candidate\n\ngo 1.25.0\n")
	writeTestFile(t, repository, "candidate_test.go", "package candidate\nimport \"testing\"\nfunc TestFixture(t *testing.T) {}\n")
	writeTestFile(t, repository, "tracked.txt", "tracked\n")
	if note != "" {
		writeTestFile(t, repository, "docs/releases/"+testVersion+".md", note)
	}
	gitRun(t, repository, "add", "--all")
	gitRun(t, repository, "commit", "-m", "candidate")
	return repository
}

func writeTestFile(t *testing.T, repository, name, contents string) {
	t.Helper()
	path := filepath.Join(repository, filepath.FromSlash(name))
	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(contents), 0o600); err != nil {
		t.Fatal(err)
	}
}

func gitRun(t *testing.T, repository string, args ...string) {
	t.Helper()
	commandArgs := append([]string{"git"}, args...)
	command := exec.Command(commandArgs[0], commandArgs[1:]...)
	command.Dir = repository
	output, err := command.CombinedOutput()
	if err != nil {
		t.Fatalf("%v: %v\n%s", commandArgs, err, output)
	}
}

func gitOutputForTest(t *testing.T, repository string, args ...string) string {
	t.Helper()
	commandArgs := append([]string{"git"}, args...)
	command := exec.Command(commandArgs[0], commandArgs[1:]...)
	command.Dir = repository
	output, err := command.Output()
	if err != nil {
		t.Fatalf("%v: %v", commandArgs, err)
	}
	return strings.TrimSpace(string(output))
}