package rustlang

import (
	"fmt"
	"os"
	"strings"
	"testing"

	"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 Rust writes are the one part of a project's
// .turbo-rust directory that is about Rust, 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 TestTheCreatedToolsFileHoldsTheCargoCommandsAndTheExampleBesideThem(t *testing.T) {
	// These are what a Rust project runs before it commits, and they are the
	// reason the file exists at all.
	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": "cargo fmt",
		"Lint":   "cargo clippy --all-targets",
		"Build":  "cargo build",
		"Test":   "cargo test",
		"Run":    "cargo run",
		"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 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) {
	// `cargo run` starts a program that may read the keyboard, and a popup
	// cannot answer one. Echo is a terminal too, as the worked example of a
	// tool in a menu of its own. 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,
		"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 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 TestTheCreatedToolsFileNamesTheRustMenuNotTheGoOne(t *testing.T) {
	// The comments explain which menu a tool lands in by naming it, and naming
	// the wrong editor's menu is the copy-and-paste mistake this catches.
	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, "Rust menu") {
		t.Errorf("the created file never names the Rust menu:\n%s", contents)
	}
	if strings.Contains(contents, "Go menu") || strings.Contains(contents, "turbo-go") {
		t.Errorf("the created file still talks about Turbo Go:\n%s", contents)
	}
}

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

	groups := loadSnippets(t, dir).Groups(string(Language))
	if len(groups) == 0 {
		t.Fatal("the created file offers nothing at all in a Rust file")
	}
	for _, group := range groups {
		for _, snippet := range group.Snippets {
			if snippet.Name == "" || snippet.Body == "" {
				t.Errorf("the created file holds an unusable snippet %+v", snippet)
			}
		}
	}
}

func TestTheCreatedSnippetsIndentWithSpacesTheWayRustfmtDoes(t *testing.T) {
	// Rust indents with four spaces. A tab that crept in would land in
	// somebody's file and be reformatted out on the next `cargo fmt`, which is
	// a diff nobody asked for.
	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(string(Language)) {
		for _, snippet := range group.Snippets {
			if strings.Contains(snippet.Body, "\t") {
				t.Errorf("%q indents with a tab:\n%q", snippet.Name, snippet.Body)
			}
		}
	}
}

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{"theme", "autosave", "autosave_delay", "-list-themes"} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

func TestEveryTemplateNamesThisEditorAndNotTheOther(t *testing.T) {
	// The three templates started as Turbo Go's. A leftover "turbo-go" in a
	// file written into somebody's Rust project is the whole class of mistake
	// this catches, and it is invisible to every other test here.
	templates := map[string]string{
		"settings": settingsTemplate,
		"snippets": snippetsTemplate,
		"tools":    toolsTemplate,
	}

	for name, template := range templates {
		t.Run(name, func(t *testing.T) {
			if strings.Contains(template, "turbo-go") {
				t.Errorf("the %s template still says turbo-go:\n%s", name, template)
			}
			if !strings.Contains(template, Slug) {
				t.Errorf("the %s template never names %s:\n%s", name, Slug, template)
			}
		})
	}
}

func TestTheSnippetsTemplateTakesExactlyTwoBlanks(t *testing.T) {
	// profile.Templates says Snippets is formatted with the ungrouped group's
	// name and the user's path, in that order. A third %s, or a stray one in a
	// comment, comes out as %!s(MISSING) in somebody's project.
	if got := strings.Count(snippetsTemplate, "%s"); got != 2 {
		t.Errorf("the snippets template has %d %%s, want 2", got)
	}
	if got := strings.Count(settingsTemplate, "%q"); got != 2 {
		t.Errorf("the settings template has %d %%q, want 2", got)
	}
	if strings.Contains(toolsTemplate, "%") {
		t.Errorf("the tools template takes no arguments but contains a %%:\n%s", toolsTemplate)
	}
}

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}}",
		"cargo new --bin {{crate name}}",
		"{{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) {
	// The examples live in comments, so none of them may become a real tool —
	// and the loader must not trip over the braces in the prose either.
	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 got := tool.Placeholders(); got != nil {
			t.Errorf("%q asks for %v; none of the five starter commands takes a value", tool.Name, got)
		}
	}
}

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)
		}
	}
}