package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

// fakeCommands installs a fixed set of PATH executables for the test.
func fakeCommands(t *testing.T, names ...string) {
	t.Helper()
	old := shellCommandList
	shellCommandList = func() []string { return names }
	t.Cleanup(func() { shellCommandList = old })
}

// shellTree lays out a directory to complete against and points DIR at it.
func shellTree(t *testing.T) string {
	t.Helper()
	dir := t.TempDir()
	for _, d := range []string{"src", "src/deep", ".hidden"} {
		if err := os.MkdirAll(filepath.Join(dir, d), 0755); err != nil {
			t.Fatal(err)
		}
	}
	for _, f := range []string{"main.go", "main_test.go", "Makefile", ".env", "src/util.go"} {
		if err := os.WriteFile(filepath.Join(dir, f), []byte("x"), 0644); err != nil {
			t.Fatal(err)
		}
	}
	old := DIR
	DIR = dir
	t.Cleanup(func() { DIR = old })
	return dir
}

func TestShellCandidatesCommandWord(t *testing.T) {
	fakeCommands(t, "vi", "vim", "view", "grep", "git")
	shellTree(t)

	cands, prefix := shellCandidates("!vi")
	if prefix != "vi" {
		t.Errorf("prefix = %q, want vi", prefix)
	}
	if strings.Join(cands, ",") != "vi,view,vim" {
		t.Errorf("candidates = %v, want vi,view,vim sorted", cands)
	}

	// a bare '!' must not dump every executable on the machine
	if cands, _ := shellCandidates("!"); len(cands) != 0 {
		t.Errorf("bare '!' offered %d candidates", len(cands))
	}
	// leading blanks are allowed, as runCommand allows them
	if cands, _ := shellCandidates("   !gi"); strings.Join(cands, ",") != "git" {
		t.Errorf("indented escape = %v, want git", cands)
	}
	// a command word with a separator is a path, not a PATH lookup
	if cands, prefix := shellCandidates("!./ma"); prefix != "ma" ||
		strings.Join(cands, ",") != "main.go,main_test.go" {
		t.Errorf("./ma = %v (prefix %q), want the local files", cands, prefix)
	}
}

func TestShellCandidatesArguments(t *testing.T) {
	fakeCommands(t, "vi")
	shellTree(t)

	// paths resolve against the project directory, where `!` commands run
	cands, prefix := shellCandidates("!vi ma")
	if prefix != "ma" || strings.Join(cands, ",") != "main.go,main_test.go" {
		t.Errorf("candidates = %v (prefix %q)", cands, prefix)
	}

	// an empty argument lists the directory — dot entries stay out of the way
	cands, prefix = shellCandidates("!vi ")
	if prefix != "" {
		t.Errorf("prefix = %q, want empty", prefix)
	}
	if strings.Join(cands, ",") != "Makefile,main.go,main_test.go,src/" {
		t.Errorf("directory listing = %v", cands)
	}

	// ... until the prefix asks for them
	if cands, _ := shellCandidates("!vi ."); strings.Join(cands, ",") != ".env,.hidden/" {
		t.Errorf("dot prefix = %v, want the hidden entries", cands)
	}

	// a directory completes with its slash, so the next Tab walks into it
	cands, prefix = shellCandidates("!vi sr")
	if prefix != "sr" || strings.Join(cands, ",") != "src/" {
		t.Errorf("directory candidate = %v (prefix %q)", cands, prefix)
	}

	// inside a directory only the basename is completed, which is what keeps
	// the candidate list readable
	cands, prefix = shellCandidates("!vi src/ut")
	if prefix != "ut" || strings.Join(cands, ",") != "util.go" {
		t.Errorf("nested candidate = %v (prefix %q), want util.go / ut", cands, prefix)
	}

	// later arguments complete the same way as the first
	if cands, _ := shellCandidates("!diff main.go ma"); strings.Join(cands, ",") != "main.go,main_test.go" {
		t.Errorf("second argument = %v", cands)
	}
}

func TestShellCandidatesAbsoluteAndHome(t *testing.T) {
	home := t.TempDir()
	t.Setenv("HOME", home)
	if err := os.WriteFile(filepath.Join(home, "notes.txt"), []byte("x"), 0644); err != nil {
		t.Fatal(err)
	}
	shellTree(t)
	fakeCommands(t, "vi")

	if cands, prefix := shellCandidates("!vi ~/no"); prefix != "no" ||
		strings.Join(cands, ",") != "notes.txt" {
		t.Errorf("~/ completion = %v (prefix %q)", cands, prefix)
	}

	abs := filepath.Join(home, "no")
	if cands, prefix := shellCandidates("!vi " + abs); prefix != "no" ||
		strings.Join(cands, ",") != "notes.txt" {
		t.Errorf("absolute completion = %v (prefix %q)", cands, prefix)
	}
}

// TestShellCompleterDoContract is the part that would corrupt the line if it
// were wrong: readline replaces the last `length` runes with a candidate, so
// the candidates must be suffixes and the length must count runes.
func TestShellCompleterDoContract(t *testing.T) {
	fakeCommands(t, "vim", "view")
	shellTree(t)
	c := completer()

	line := []rune("!vi")
	got, length := c.Do(line, len(line))
	if length != 2 { // "vi" — the '!' is not part of the word
		t.Fatalf("length = %d, want 2", length)
	}
	// rebuilding the line from prefix + candidate must give the full word
	for i, g := range got {
		full := string(line[:len(line)-length]) + string(line[len(line)-length:]) + string(g)
		if full != "!vim" && full != "!view" {
			t.Errorf("candidate %d rebuilds to %q", i, full)
		}
	}

	// a non-'!' line still goes to the builtin command tree (which appends its
	// own trailing space on a unique match)
	line = []rune("stat")
	got, length = c.Do(line, len(line))
	if length != 4 || len(got) == 0 || !strings.HasPrefix(string(got[0]), "us") {
		t.Errorf("builtin completion = %q, %d; want a candidate starting \"us\" at 4", got, length)
	}

	// a multi-byte prefix must be measured in runes, not bytes
	if _, n := runeSuffixes([]string{"übermorgen"}, "üb"); n != 2 {
		t.Errorf("runeSuffixes length = %d, want 2 runes", n)
	}
}

// TestPathExecutablesFindsRealBinaries checks the PATH scan against a directory
// it controls: only files with an execute bit, no directories.
func TestPathExecutablesFindsRealBinaries(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "runnable"), []byte("#!/bin/sh\n"), 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "plainfile"), []byte("x"), 0644); err != nil {
		t.Fatal(err)
	}
	if err := os.MkdirAll(filepath.Join(dir, "subdir"), 0755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("PATH", dir)

	// pathExecutables caches for the session, so exercise the scan directly
	var names []string
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	for _, e := range entries {
		fi, err := e.Info()
		if err != nil || fi.IsDir() || fi.Mode().Perm()&0o111 == 0 {
			continue
		}
		names = append(names, e.Name())
	}
	if strings.Join(names, ",") != "runnable" {
		t.Errorf("executable scan = %v, want only runnable", names)
	}
}