package pythonlang

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 Python writes are the one part of a project's
// .turbo-python directory that is about Python, 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())
}

// createTools writes a project's tools file and returns the project directory.
func createTools(t *testing.T) string {
	t.Helper()

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

// createSnippets writes a project's snippets file and returns the directory.
func createSnippets(t *testing.T) string {
	t.Helper()
	noUserSnippets(t)

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

// createSettings writes a project's settings file and returns the directory.
func createSettings(t *testing.T) string {
	t.Helper()

	dir := t.TempDir()
	if _, err := settings.Create(Profile(), dir, "turbo-classic"); err != nil {
		t.Fatalf("settings.Create() error = %v", err)
	}
	return dir
}

// 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])
}

// --- the tools file ---------------------------------------------------------

func TestTheCreatedToolsFileHoldsTheSixCommandsAProjectRuns(t *testing.T) {
	// These are what a Python project runs on itself, and they are the reason
	// the file exists at all. Everything goes through uv, so none of them needs
	// an environment to have been activated first.
	byName := map[string]string{}
	for _, tool := range loadTools(t, createTools(t)).In("Python") {
		byName[plain(tool.Name)] = tool.Command
	}

	want := map[string]string{
		"Environment": "uv venv {{directory, usually .venv}}",
		"Sync":        "uv sync",
		"Format":      "uv run ruff format .",
		"Lint":        "uv run ruff check .",
		"Test":        "uv run pytest",
		"Run":         "uv run {{script}}",
	}
	for name, command := range want {
		if got := byName[name]; got != command {
			t.Errorf("%s runs %q, want %q", name, got, command)
		}
	}
	if len(byName) != len(want) {
		t.Errorf("the Python menu holds %d tools, want %d: %v", len(byName), len(want), byName)
	}
}

// Creating the environment is the step in Python that has to happen before any
// of the others can, and the one a newcomer to a project most often has not
// done — so it is the first item in the menu rather than the last.
func TestCreatingTheEnvironmentIsTheFirstToolInTheMenu(t *testing.T) {
	python := loadTools(t, createTools(t)).In("Python")

	if len(python) == 0 {
		t.Fatal("the Python menu is empty")
	}
	if got := plain(python[0].Name); got != "Environment" {
		t.Errorf("the first tool in the menu is %q, want %q", got, "Environment")
	}
}

// The directory is asked for rather than fixed: .venv is the usual answer and
// not the only one, and a tool that asks is also the file's live demonstration
// that asking is possible.
func TestTheEnvironmentToolAsksWhereToPutIt(t *testing.T) {
	for _, tool := range loadTools(t, createTools(t)).Tools() {
		if plain(tool.Name) != "Environment" {
			continue
		}

		asked := tool.Placeholders()
		if len(asked) != 1 {
			t.Fatalf("Environment asks for %d values, want 1: %v", len(asked), asked)
		}
		if !strings.Contains(asked[0].Label, ".venv") {
			t.Errorf("it asks for %q, which never mentions .venv", asked[0].Label)
		}
		if asked[0].Raw {
			t.Errorf("it asks for %q unquoted; a directory with a space in it would become two arguments", asked[0].Label)
		}
		return
	}
	t.Fatal("there is no Environment tool")
}

func TestOnlyTheTwoToolsThatNeedAValueAskForOne(t *testing.T) {
	// Every other command is complete as it stands, and a box in front of a
	// command that has nothing to ask is a keystroke for nothing.
	asking := map[string]bool{"Environment": true, "Run": true}

	for _, tool := range loadTools(t, createTools(t)).Tools() {
		name := plain(tool.Name)
		if got := len(tool.Placeholders()) > 0; got != asking[name] {
			t.Errorf("%s asks for a value: %t, want %t (%q)", name, got, asking[name], tool.Command)
		}
	}
}

func TestTheCreatedToolsCarryHotKeysUniqueWithinTheirMenu(t *testing.T) {
	// Six items in a menu are worth reaching with one keystroke each. Two menus
	// may each have an E, which is why the check is per menu.
	list := loadTools(t, createTools(t))

	for _, menu := range list.MenuNames() {
		seen := map[rune]string{}
		for _, tool := range list.In(menu) {
			key := hotKey(tool.Name)
			if key == 0 {
				t.Errorf("%q in the %s menu has no hot key", tool.Name, menu)
				continue
			}
			if other, clash := seen[key]; clash {
				t.Errorf("%q and %q in the %s menu both answer to %c", other, tool.Name, menu, 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.
	for _, tool := range loadTools(t, createTools(t)).Tools() {
		if tool.Output == "" {
			t.Errorf("%q leaves its output to the default rather than saying it", tool.Name)
		}
	}
}

func TestRunIsTheOneToolchainCommandInATerminal(t *testing.T) {
	// A Python script usually reads the keyboard, runs long, or both, and a
	// popup can answer neither. The Echo example is in a terminal too, but it
	// is in a menu of its own and is there to demonstrate the menu key.
	for _, tool := range loadTools(t, createTools(t)).In("Python") {
		want := tools.OutputPopup
		if plain(tool.Name) == "Run" {
			want = tools.OutputTerminal
		}
		if got := tool.Where(); got != want {
			t.Errorf("%s goes to %q, want %q", plain(tool.Name), got, want)
		}
	}
}

func TestTheCreatedToolsFileExplainsItself(t *testing.T) {
	contents := readFile(t, tools.Path(Profile(), createTools(t)))

	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 TestTheCreatedToolsFileNamesThePythonMenuAndNoOtherEditorsMenu(t *testing.T) {
	// The comments explain which menu a tool lands in by naming it. Naming the
	// menu of the editor this one was adapted from is the copy-and-paste
	// mistake this catches, and it is invisible to every other test.
	contents := readFile(t, tools.Path(Profile(), createTools(t)))

	if !strings.Contains(contents, "Python menu") {
		t.Errorf("the created file never names the Python menu:\n%s", contents)
	}
	for _, other := range []string{"Go menu", "Rust menu", "turbo-go", "turbo-rust", "cargo"} {
		if strings.Contains(contents, other) {
			t.Errorf("the created file still talks about %q:\n%s", other, contents)
		}
	}
}

func TestTheCreatedToolsFileShowsHowToUseAnotherMenu(t *testing.T) {
	contents := readFile(t, tools.Path(Profile(), createTools(t)))

	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 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.
	contents := readFile(t, tools.Path(Profile(), createTools(t)))

	for _, want := range []string{
		"{{label}}",
		"uv add {{package}}",
		"{{extra flags...}}",
		"Double braces, not single",
	} {
		if !strings.Contains(contents, want) {
			t.Errorf("the created file never mentions %q:\n%s", want, contents)
		}
	}
}

// --- the snippets file ------------------------------------------------------

func TestTheCreatedSnippetsFileHoldsUsablePythonSnippets(t *testing.T) {
	groups := loadSnippets(t, createSnippets(t)).Groups(string(Language))

	if len(groups) == 0 {
		t.Fatal("the created file offers nothing at all in a Python 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 TestTheCreatedSnippetsIndentWithFourSpacesTheWayPEP8Does(t *testing.T) {
	// A tab inserted into a file indented with spaces is an indentation error
	// in Python, not a formatting quibble: the file stops running.
	for _, group := range loadSnippets(t, createSnippets(t)).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)
			}
			for _, line := range strings.Split(snippet.Body, "\n") {
				indent := len(line) - len(strings.TrimLeft(line, " "))
				if indent%4 != 0 {
					t.Errorf("%q has a line indented by %d spaces:\n%q", snippet.Name, indent, line)
				}
			}
		}
	}
}

// Every snippet must be Python that runs, not Python that looks right — the
// scanner is the nearest thing to a parser this repository has, and a snippet
// whose whole body comes out as one colour is a snippet with an unclosed
// string in it.
func TestEverySnippetBodyColoursAsMoreThanOneThing(t *testing.T) {
	for _, group := range loadSnippets(t, createSnippets(t)).Groups(string(Language)) {
		for _, snippet := range group.Snippets {
			classes := map[syntax.Class]bool{}
			for _, line := range Highlight(snippet.Body) {
				for _, span := range line {
					classes[span.Class] = true
				}
			}
			if len(classes) < 2 {
				t.Errorf("%q colours as %d classes:\n%s", snippet.Name, len(classes), snippet.Body)
			}
		}
	}
}

func TestTheCreatedSnippetsFileExplainsItself(t *testing.T) {
	contents := readFile(t, snippets.ProjectPath(Profile(), createSnippets(t)))

	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 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. Iterating the registry rather than a
	// list is what stops the comment falling behind it, as turbo-rust's did
	// when turbo-core learnt YAML, XML and Dockerfiles.
	Register()
	contents := readFile(t, snippets.ProjectPath(Profile(), createSnippets(t)))

	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)
		}
	}
}

// --- the settings file ------------------------------------------------------

func TestTheCreatedSettingsFileExplainsItself(t *testing.T) {
	contents := readFile(t, settings.Path(Profile(), createSettings(t)))

	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 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 this default lives here and not in the library.
	project := createSettings(t)

	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 contract the three templates are held to ---------------------------

// 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
	// 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 TestEveryTemplateNamesThisEditorAndNotTheOnesItWasAdaptedFrom(t *testing.T) {
	// The three templates started as Turbo Rust's. A leftover "turbo-rust" in a
	// file written into somebody's Python project is the whole class of mistake
	// this catches.
	templates := map[string]string{
		"settings": settingsTemplate,
		"snippets": snippetsTemplate,
		"tools":    toolsTemplate,
	}

	for name, template := range templates {
		t.Run(name, func(t *testing.T) {
			for _, other := range []string{"turbo-go", "turbo-rust", "cargo", "gopls", "rust-analyzer"} {
				if strings.Contains(template, other) {
					t.Errorf("the %s template still says %q:\n%s", name, other, template)
				}
			}
			if !strings.Contains(template, Slug) {
				t.Errorf("the %s template never names %s:\n%s", name, Slug, template)
			}
		})
	}
}