package golang

import (
	"errors"
	"fmt"
	"os"
	"slices"
	"strings"
	"testing"

	"rickub.com/turbo-editors/turbo-core/acp"
	"rickub.com/turbo-editors/turbo-core/settings"
	"rickub.com/turbo-editors/turbo-core/snippets"
	"rickub.com/turbo-editors/turbo-core/syntax"
	"rickub.com/turbo-editors/turbo-core/tools"
)

// The starter files Turbo Go writes are the one part of a project's .turbo-go
// directory that is about Go, so this is where what is *in* them is checked.
// That the file written is the profile's template at all is turbo-core's test.

// noUserSnippets points the user's own snippets at an empty directory, so a
// test never reads whoever is running it.
func noUserSnippets(t *testing.T) {
	t.Helper()
	t.Setenv(Profile().SnippetDirEnvVar(), t.TempDir())
}

// loadTools reads a project's tools, failing the test if it cannot.
func loadTools(t *testing.T, dir string) tools.List {
	t.Helper()

	list, err := tools.Load(Profile(), dir)
	if err != nil {
		t.Fatalf("tools.Load(%q) error = %v", dir, err)
	}
	return list
}

// loadSnippets reads a project's snippets, failing the test if it cannot.
func loadSnippets(t *testing.T, dir string) snippets.List {
	t.Helper()

	list, err := snippets.Load(Profile(), dir)
	if err != nil {
		t.Fatalf("snippets.Load(%q) error = %v", dir, err)
	}
	return list
}

// readFile returns a file's contents.
func readFile(t *testing.T, path string) string {
	t.Helper()

	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("reading %s: %v", path, err)
	}
	return string(data)
}

// plain strips the tilde hot-key markers from a label.
func plain(label string) string { return strings.ReplaceAll(label, "~", "") }

// hotKey returns the character between the tildes, or 0 when there is none.
func hotKey(label string) rune {
	first := strings.IndexByte(label, '~')
	if first < 0 || first+1 >= len(label) {
		return 0
	}
	return rune(label[first+1])
}

func TestTheCreatedToolsFileHoldsTheGoCommandsAndTheExamplesThatTeachTheFormat(t *testing.T) {
	// The first five are what a Go project runs before it commits, and they are
	// the reason the file exists at all. The three after them are there to
	// teach the format itself — a value the editor asks for, a menu of the
	// tool's own, an output that is not the default — and a starter file that
	// only listed the five would leave all three undiscoverable.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	byName := map[string]string{}
	for _, tool := range loadTools(t, dir).Tools() {
		byName[plain(tool.Name)] = tool.Command
	}

	want := map[string]string{
		"Format":      "gofmt -l -w .",
		"Lint":        "go vet ./...",
		"Build":       "go build ./...",
		"Test":        "go test ./...",
		"Run":         "go run .",
		"Grep":        "grep -rn {{pattern}} --include='*.go' .",
		"Init module": "go mod init {{module path}}",
		"Echo":        "echo 🎉 tada!",
	}
	for name, command := range want {
		if got := byName[name]; got != command {
			t.Errorf("%s runs %q, want %q", name, got, command)
		}
	}
	for name := range byName {
		if _, ok := want[name]; !ok {
			t.Errorf("the created file holds a tool this test does not know about: %q", name)
		}
	}
}

func TestTheCreatedToolsCarryHotKeys(t *testing.T) {
	// Five items in a menu are worth reaching with one keystroke each.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	seen := map[rune]string{}
	for _, tool := range loadTools(t, dir).Tools() {
		key := hotKey(tool.Name)
		if key == 0 {
			t.Errorf("%q has no hot key", tool.Name)
			continue
		}
		if other, clash := seen[key]; clash {
			t.Errorf("%q and %q both answer to %c", other, tool.Name, key)
		}
		seen[key] = tool.Name
	}
}

func TestTheCreatedToolsFileDoesNotClaimEverythingRunsInATerminal(t *testing.T) {
	// The header said so before output existed, and left the file contradicting
	// itself two lines above the key that says otherwise.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	contents := readFile(t, tools.Path(Profile(), dir))
	if strings.Contains(contents, "runs it in a terminal window of its own") {
		t.Errorf("the header still claims every tool runs in a terminal:\n%s", contents)
	}
}

func TestTheCreatedToolsFileExplainsItself(t *testing.T) {
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	contents := readFile(t, tools.Path(Profile(), dir))
	for _, want := range []string{"[[tool]]", "sh -c", "hot key", "popup", "terminal", "editor", "./..."} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestTheCreatedToolsFileNamesAnOutputForEveryTool(t *testing.T) {
	// The key is the interesting part of the format, and a file where it only
	// appears once is a file where nobody notices it exists.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	for _, tool := range loadTools(t, dir).Tools() {
		if tool.Output == "" {
			t.Errorf("%q leaves its output to the default rather than saying it", tool.Name)
		}
	}
}

func TestEachToolGoesWhereItsOwnOutputBelongs(t *testing.T) {
	// All three destinations appear, because a starter file is where somebody
	// finds out that the key has more than one value. Run and Echo are
	// terminals: a program that reads the keyboard has to be able to be
	// answered, and a popup cannot do that. Grep prints a list worth keeping
	// beside the code and searching with Ctrl-F, which is what an editing
	// window is for. The rest say something short and are read once.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	want := map[string]tools.Output{
		"Format":      tools.OutputPopup,
		"Lint":        tools.OutputPopup,
		"Build":       tools.OutputPopup,
		"Test":        tools.OutputPopup,
		"Run":         tools.OutputTerminal,
		"Grep":        tools.OutputEditor,
		"Init module": tools.OutputPopup,
		"Echo":        tools.OutputTerminal,
	}
	for _, tool := range loadTools(t, dir).Tools() {
		name := plain(tool.Name)
		if got := tool.Where(); got != want[name] {
			t.Errorf("%s goes to %q, want %q", name, got, want[name])
		}
	}
}

func TestTheCreatedToolsFileShowsHowToUseAnotherMenu(t *testing.T) {
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	contents := readFile(t, tools.Path(Profile(), dir))
	for _, want := range []string{"menu says which menu", `menu = "Tools"`} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never shows %q:\n%s", want, contents)
		}
	}
}

func TestTheCreatedSnippetsFilesTabsSurviveTOML(t *testing.T) {
	// A Go snippet is indented with tabs, and every step between the template
	// and the editor is somewhere one can be lost: the multi-line TOML string,
	// the decoder, and the editor's own re-indentation on insertion. Asserting
	// on a tab the body is known to contain is what catches that.
	noUserSnippets(t)
	dir := t.TempDir()
	if _, err := snippets.Create(Profile(), dir); err != nil {
		t.Fatalf("snippets.Create() error = %v", err)
	}

	for _, group := range loadSnippets(t, dir).Groups("go") {
		for _, snippet := range group.Snippets {
			if snippet.Name != "main" {
				continue
			}
			if !strings.Contains(snippet.Body, "\tfmt.Println") {
				t.Errorf("the body is %q; the tab did not survive", snippet.Body)
			}
			return
		}
	}
	t.Fatal("the created file has no \"main\" snippet")
}

func TestTheCreatedSnippetsFileExplainsItself(t *testing.T) {
	noUserSnippets(t)
	dir := t.TempDir()
	if _, err := snippets.Create(Profile(), dir); err != nil {
		t.Fatalf("snippets.Create() error = %v", err)
	}

	contents := readFile(t, snippets.ProjectPath(Profile(), dir))
	for _, want := range []string{"[[snippet]]", "languages", "group", "General", snippets.UserPath(Profile())} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestTheCreatedSettingsFileExplainsItself(t *testing.T) {
	project := t.TempDir()
	if _, err := settings.Create(Profile(), project, "turbo-classic"); err != nil {
		t.Fatalf("settings.Create() error = %v", err)
	}

	contents := readFile(t, settings.Path(Profile(), project))
	for _, want := range []string{"-list-themes", "autosave_delay", "-theme flag"} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestTheCreatedToolsFileExplainsHowToAskForAValue(t *testing.T) {
	// A parameterised tool is only discoverable if the file people get says the
	// syntax exists. The double-brace warning is here too, because somebody
	// reading this file may well have an awk one-liner in mind.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	contents := readFile(t, tools.Path(Profile(), dir))
	for _, want := range []string{
		"{{label}}",
		"go mod init {{module path}}",
		"{{extra flags...}}",
		"Double braces, not single",
	} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestTheCreatedToolsFileStillLoadsWithItsPlaceholderExamples(t *testing.T) {
	// Two of the starter tools ask for a value, on purpose: a syntax explained
	// only in a comment is a syntax nobody tries. What they ask for is checked
	// here rather than left to the prose, because the braces also appear in the
	// file's *comments* — `{{label}}`, `{{extra flags...}}`, and an awk
	// one-liner warning against single ones — and a loader that read those as
	// tools would ask for something nobody wrote a command for.
	dir := t.TempDir()
	if _, err := tools.Create(Profile(), dir); err != nil {
		t.Fatalf("tools.Create() error = %v", err)
	}

	want := map[string][]tools.Placeholder{
		"Grep":        {{Label: "pattern"}},
		"Init module": {{Label: "module path"}},
	}
	for _, tool := range loadTools(t, dir).Tools() {
		name := plain(tool.Name)
		got := tool.Placeholders()
		if !slices.Equal(got, want[name]) {
			t.Errorf("%q asks for %v, want %v", name, got, want[name])
		}
	}
}

func TestTheCreatedSnippetsFileListsEveryLanguageTheEditorKnows(t *testing.T) {
	// The comment is where a user finds out what they may write in a languages
	// key. One that omits a language the editor colours sends them looking for
	// a feature that is already there.
	noUserSnippets(t)
	dir := t.TempDir()
	if _, err := snippets.Create(Profile(), dir); err != nil {
		t.Fatalf("snippets.Create() error = %v", err)
	}

	contents := readFile(t, snippets.ProjectPath(Profile(), dir))
	for _, language := range syntax.Registered() {
		if !strings.Contains(contents, string(language)) {
			t.Errorf("the created file never mentions the %q language:\n%s", language, contents)
		}
	}
}

func TestTheCreatedSettingsFileTurnsAutosaveOn(t *testing.T) {
	// A project that has gone to the trouble of creating a settings file has
	// said what it wants. The file is the visible, editable place to say
	// otherwise, which is why the default lives here and not in the library.
	project := t.TempDir()
	if _, err := settings.Create(Profile(), project, "turbo-classic"); err != nil {
		t.Fatalf("settings.Create() error = %v", err)
	}

	loaded, err := settings.Load(Profile(), project)
	if err != nil {
		t.Fatalf("settings.Load() error = %v", err)
	}
	if !loaded.Autosave {
		t.Errorf("the created settings file leaves autosave off:\n%s", readFile(t, settings.Path(Profile(), project)))
	}
	if loaded.AutosaveDelay != settings.DefaultAutosaveDelay {
		t.Errorf("AutosaveDelay = %v, want the library default %v", loaded.AutosaveDelay, settings.DefaultAutosaveDelay)
	}
}

func TestAProjectWithNoSettingsFileStillDoesNotAutosave(t *testing.T) {
	// The other half of the decision. Turning autosave on for a project that
	// never opted in would mean the editor writing to disk in any directory it
	// is started in, which is a different and much larger claim.
	if settings.Default().Autosave {
		t.Error("settings.Default() autosaves; a project with no settings file never opted in")
	}
}

// The three embedded templates and the blanks profile.Templates says each one
// takes. Kept together so that adding a verb to a .tmpl file without saying so
// here fails, which is the guard the constants used to get for free by sitting
// next to the contract.
var embeddedTemplates = []struct {
	name     string
	body     string
	verb     string
	blanks   int
	filledBy []any
}{
	{"settings.toml.tmpl", settingsTemplate, "%q", 2, []any{"turbo-classic", "2s"}},
	{"snippets.toml.tmpl", snippetsTemplate, "%s", 2, []any{"General", "/tmp/snippets.toml"}},
	{"tools.toml.tmpl", toolsTemplate, "%", 0, nil},
}

func TestEveryTemplateIsEmbeddedAndNotEmpty(t *testing.T) {
	// go:embed fails to compile when a file is missing, but an empty file
	// compiles happily and writes an empty starter file into somebody's
	// project.
	for _, template := range embeddedTemplates {
		if len(template.body) == 0 {
			t.Errorf("%s embedded as nothing", template.name)
		}
	}
}

func TestEveryTemplateTakesTheBlanksItsContractPromises(t *testing.T) {
	// profile.Templates documents the count and the verb of each. The
	// templates now live in files of their own, so nothing but this notices a
	// verb added, removed, or changed.
	for _, template := range embeddedTemplates {
		if got := strings.Count(template.body, template.verb); got != template.blanks {
			t.Errorf("%s holds %d %q, want %d", template.name, got, template.verb, template.blanks)
		}
	}
}

func TestFillingATemplateLeavesNoFormattingMarker(t *testing.T) {
	// Go writes %!q(MISSING) or %!(EXTRA …) into the output rather than
	// failing, so a template with the wrong number of blanks produces a file
	// that is written, opened, and wrong.
	for _, template := range embeddedTemplates {
		filled := template.body
		if template.filledBy != nil {
			filled = fmt.Sprintf(template.body, template.filledBy...)
		}
		if strings.Contains(filled, "%!") {
			t.Errorf("%s filled to:\n%s", template.name, filled)
		}
	}
}

func TestTheCreatedAgentsFileFillsBothOfItsBlanks(t *testing.T) {
	// The template takes two different values — the project directory, which
	// the example agent's arguments point into, and the user's own file, which
	// a comment names. Go writes %!s(MISSING) into the output rather than
	// failing, so a miscounted verb produces a starter file that is written,
	// opened, and wrong.
	dir := t.TempDir()
	if _, err := acp.Create(Profile(), dir); err != nil {
		t.Fatalf("acp.Create() error = %v", err)
	}

	contents := readFile(t, acp.ProjectPath(Profile(), dir))
	if strings.Contains(contents, "%!") {
		t.Errorf("the created file has an unfilled verb in it:\n%s", contents)
	}
	if want := Profile().ProjectDir() + "/agent.yaml"; !strings.Contains(contents, want) {
		t.Errorf("the example agent does not point at %q:\n%s", want, contents)
	}
	if want := acp.UserPath(Profile()); want != "" && !strings.Contains(contents, want) {
		t.Errorf("the created file never names the user's own file %q:\n%s", want, contents)
	}
}

func TestTheCreatedAgentsFileLoadsBackAsOneAgent(t *testing.T) {
	// The file is mostly comments, and a comment carrying a [[agent]] example
	// that the loader read as real would put an agent nobody configured into
	// the menu.
	dir := t.TempDir()
	if _, err := acp.Create(Profile(), dir); err != nil {
		t.Fatalf("acp.Create() error = %v", err)
	}

	list, err := acp.Load(Profile(), dir)
	if err != nil {
		t.Fatalf("acp.Load() error = %v", err)
	}
	if list.Len() != 1 {
		t.Fatalf("the created file holds %d agents, want 1: %v", list.Len(), list.Agents())
	}

	agent := list.Agents()[0]
	if agent.Command != "docker" {
		t.Errorf("the example agent runs %q, want docker", agent.Command)
	}
	if want := "agent serve acp"; !strings.Contains(agent.CommandLine(), want) {
		t.Errorf("the example command line is %q, want %q in it", agent.CommandLine(), want)
	}
}

func TestTheCreatedAgentsFileExplainsItself(t *testing.T) {
	// The keys and the window's keyboard are both invisible otherwise: this is
	// the only document a user is handed by the editor itself.
	dir := t.TempDir()
	if _, err := acp.Create(Profile(), dir); err != nil {
		t.Fatalf("acp.Create() error = %v", err)
	}

	contents := readFile(t, acp.ProjectPath(Profile(), dir))
	for _, want := range []string{
		"[[agent]]", "name", "command", "args", "env", "cwd",
		"agentclientprotocol.com",
		"Alt-Enter", "Ctrl-W", "Esc",
	} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestCreatingAgentsTwiceLeavesTheFirstAlone(t *testing.T) {
	dir := t.TempDir()
	path, err := acp.Create(Profile(), dir)
	if err != nil {
		t.Fatalf("acp.Create() error = %v", err)
	}
	if err := os.WriteFile(path, []byte("# mine\n"), 0o644); err != nil {
		t.Fatalf("writing over it: %v", err)
	}

	if _, err := acp.Create(Profile(), dir); !errors.Is(err, acp.ErrExists) {
		t.Errorf("acp.Create() error = %v, want ErrExists", err)
	}
	if got := readFile(t, path); got != "# mine\n" {
		t.Errorf("the file was overwritten: %q", got)
	}
}