package terminal

import (
	"testing"
	"unicode/utf16"
)

// These run on every platform: they check the shapes Windows wants things in,
// not Windows itself. The API calls that consume them are compiled with
// GOOS=windows and have never been run by this project's authors — see
// README.md.

func TestWindowsShellIsComspecOrCmd(t *testing.T) {
	if got := windowsShell(`C:\Windows\system32\cmd.exe`); got != `C:\Windows\system32\cmd.exe` {
		t.Errorf("windowsShell(COMSPEC) = %q, want COMSPEC itself", got)
	}
	if got := windowsShell(""); got != "cmd.exe" {
		t.Errorf("windowsShell(\"\") = %q, want the fallback cmd.exe", got)
	}
}

func TestTheEnvironmentBlockIsNulSeparatedAndDoubleNulEnded(t *testing.T) {
	block := environmentBlock([]string{"A=1", "TERM=xterm-256color"})

	want := append(utf16.Encode([]rune("A=1")), 0)
	want = append(want, utf16.Encode([]rune("TERM=xterm-256color"))...)
	want = append(want, 0, 0)

	if len(block) != len(want) {
		t.Fatalf("block has %d code units, want %d", len(block), len(want))
	}
	for i := range want {
		if block[i] != want[i] {
			t.Fatalf("block differs at %d: %v, want %v", i, block, want)
		}
	}
}

func TestTheEnvironmentBlockKeepsNonASCII(t *testing.T) {
	// UTF-16, not bytes: a variable holding an accent must survive.
	block := environmentBlock([]string{"NAME=élan"})

	if got := string(utf16.Decode(block[:len(block)-2])); got != "NAME=élan" {
		t.Errorf("the block decodes to %q, want NAME=élan", got)
	}
}

func TestAnEmptyEnvironmentIsTwoNuls(t *testing.T) {
	// A single NUL would be a block whose first entry is empty and which then
	// runs off the end; nil would mean "inherit", which the caller never
	// wants because TERM is set. Two NULs is the documented empty block.
	if got := environmentBlock(nil); len(got) != 2 || got[0] != 0 || got[1] != 0 {
		t.Errorf("environmentBlock(nil) = %v, want two NULs", got)
	}
}

func TestCmdExeGetsItsCommandVerbatimInsideOnePairOfQuotes(t *testing.T) {
	// cmd.exe /S /C strips the first and last quote and parses the rest by
	// its own rules, so a quote inside the command must reach it unescaped.
	got := windowsCommandLine(`C:\Windows\system32\cmd.exe`, []string{"/S", "/C", `echo "hello world" && node --test`})

	want := `"C:\Windows\system32\cmd.exe" /S /C "echo "hello world" && node --test"`
	if got != want {
		t.Errorf("windowsCommandLine() = %s, want %s", got, want)
	}
}

func TestCmdExeIsRecognisedWhateverItsCaseOrPath(t *testing.T) {
	for _, program := range []string{"cmd.exe", "CMD.EXE", `C:\WINDOWS\System32\Cmd.exe`, "cmd"} {
		if !isCmdExe(program) {
			t.Errorf("isCmdExe(%q) = false, want true", program)
		}
	}
	for _, program := range []string{"pwsh.exe", `C:\Program Files\PowerShell\7\pwsh.exe`, "bash"} {
		if isCmdExe(program) {
			t.Errorf("isCmdExe(%q) = true, want false", program)
		}
	}
}

func TestAnInteractiveCmdExeHasNoSwitchesToSpecialCase(t *testing.T) {
	// No arguments: the ordinary composition, which is just the program.
	if got := windowsCommandLine("cmd.exe", nil); got != "cmd.exe" {
		t.Errorf("windowsCommandLine(cmd.exe) = %q, want cmd.exe", got)
	}
}

func TestOtherProgramsGetCRuntimeQuoting(t *testing.T) {
	// The rule syscall.EscapeArg follows: quotes around an argument with a
	// space, \" for a quote, backslashes doubled only before a quote.
	tests := []struct {
		program string
		args    []string
		want    string
	}{
		{"pwsh.exe", []string{"-NoLogo"}, `pwsh.exe -NoLogo`},
		{`C:\Program Files\PowerShell\7\pwsh.exe`, []string{"-c", "echo hi"}, `"C:\Program Files\PowerShell\7\pwsh.exe" -c "echo hi"`},
		{"node", []string{"-e", `console.log("x")`}, `node -e "console.log(\"x\")"`},
		{"node", []string{`C:\path with space\`}, `node "C:\path with space\\"`},
		{"node", []string{`a\"b`}, `node "a\\\"b"`},
		{"node", []string{""}, `node ""`},
	}

	for _, test := range tests {
		if got := windowsCommandLine(test.program, test.args); got != test.want {
			t.Errorf("windowsCommandLine(%q, %q) = %s, want %s", test.program, test.args, got, test.want)
		}
	}
}

func TestProgramNameDropsWindowsAndUnixPaths(t *testing.T) {
	for program, want := range map[string]string{
		`C:\Windows\system32\cmd.exe`: "cmd.exe",
		"/bin/sh":                     "sh",
		"pwsh.exe":                    "pwsh.exe",
	} {
		if got := programName(program); got != want {
			t.Errorf("programName(%q) = %q, want %q", program, got, want)
		}
	}
}