package multiplex

import (
	"errors"
	"fmt"
	"strings"
	"testing"
)

// fake records commands and answers like tmux and zellij would.
type fake struct {
	env       map[string]string
	installed map[string]bool
	sessions  map[string]bool
	calls     []string
	exec      []string
	files     map[string]string
	syncState string
	n         int
}

func newFake(env map[string]string, installed ...string) *fake {
	f := &fake{env: env, installed: map[string]bool{}, sessions: map[string]bool{}, files: map[string]string{}, syncState: "off"}
	for _, name := range installed {
		f.installed[name] = true
	}
	return f
}

func (f *fake) Output(argv ...string) (string, error) {
	f.calls = append(f.calls, strings.Join(argv, " "))
	f.n++
	switch argv[1] {
	case "new-window", "new-session":
		return fmt.Sprintf("@%d %%%d", f.n, f.n), nil
	case "split-window":
		return fmt.Sprintf("%%%d", f.n), nil
	case "has-session":
		if f.sessions[strings.TrimPrefix(argv[3], "=")] {
			return "", nil
		}
		return "", errors.New("can't find session")
	case "show-window-options":
		return f.syncState, nil
	}
	return "", nil
}
func (f *fake) Exec(argv ...string) error { f.exec = argv; return nil }
func (f *fake) LookPath(name string) (string, error) {
	if f.installed[name] {
		return "/usr/bin/" + name, nil
	}
	return "", errors.New("not found")
}
func (f *fake) Getenv(key string) string { return f.env[key] }
func (f *fake) WriteFile(path string, data []byte) error {
	f.files[path] = string(data)
	return nil
}

func panes(names ...string) []Pane {
	out := make([]Pane, 0, len(names))
	for _, name := range names {
		out = append(out, Pane{Title: name, Argv: []string{"/usr/bin/netssh", name}})
	}
	return out
}

func TestDetect(t *testing.T) {
	for _, tc := range []struct {
		requested string
		env       map[string]string
		installed []string
		want      string
	}{
		{"", map[string]string{"TMUX": "/tmp/tmux"}, []string{"tmux", "zellij"}, Tmux},
		{"auto", map[string]string{"ZELLIJ": "0"}, []string{"tmux", "zellij"}, Zellij},
		{"", nil, []string{"tmux", "zellij"}, Tmux},
		{"", nil, []string{"zellij"}, Zellij},
		{"zellij", map[string]string{"TMUX": "x"}, []string{"tmux", "zellij"}, Zellij},
	} {
		got, err := Detect(tc.requested, newFake(tc.env, tc.installed...))
		if err != nil || got != tc.want {
			t.Errorf("%+v: got %q %v", tc, got, err)
		}
	}
	if _, err := Detect("", newFake(nil)); !errors.Is(err, ErrNone) {
		t.Errorf("nothing installed: %v", err)
	}
	if _, err := Detect("tmux", newFake(nil, "zellij")); err == nil {
		t.Error("missing requested multiplexer accepted")
	}
}

func TestTmuxInside(t *testing.T) {
	f := newFake(map[string]string{"TMUX": "/tmp/tmux-1/default"}, "tmux")
	if err := Open(Tmux, panes("a", "b", "c"), Options{Label: "pve", Sync: true}, f); err != nil {
		t.Fatal(err)
	}
	script := "sh -c " + paneScript + " netssh-pane /usr/bin/netssh "
	want := []string{
		"tmux new-window -P -F #{window_id} #{pane_id} -n pve " + script + "a",
		"tmux split-window -t @1 -P -F #{pane_id} " + script + "b",
		"tmux select-layout -t @1 tiled",
		"tmux split-window -t @1 -P -F #{pane_id} " + script + "c",
		"tmux select-layout -t @1 tiled",
		"tmux set-option -p -t %1 @netssh_host a",
		"tmux set-option -p -t %2 @netssh_host b",
		"tmux set-option -p -t %4 @netssh_host c",
		"tmux set-window-option -t @1 pane-border-status top",
		"tmux set-window-option -t @1 pane-border-format  #{@netssh_host}#{?pane_synchronized, [SYNC],} ",
		"tmux set-window-option -t @1 synchronize-panes on",
		"tmux select-window -t @1",
	}
	if strings.Join(f.calls, "\n") != strings.Join(want, "\n") {
		t.Fatalf("calls:\n%s\nwant:\n%s", strings.Join(f.calls, "\n"), strings.Join(want, "\n"))
	}
	if f.exec != nil {
		t.Fatal("inside tmux must not attach")
	}
}

func TestTmuxOutsideSplitsWindowsAndAvoidsSessionNames(t *testing.T) {
	f := newFake(nil, "tmux")
	f.sessions["netssh-pve"] = true
	var hints []string
	err := Open(Tmux, panes("a", "b", "c"), Options{Label: "pve", PerWindow: 2, Hint: func(s string) { hints = append(hints, s) }}, f)
	if err != nil {
		t.Fatal(err)
	}
	joined := strings.Join(f.calls, "\n")
	for _, want := range []string{
		"tmux has-session -t =netssh-pve-2",
		"tmux new-session -d -x 240 -y 70 -s netssh-pve-2 -P -F #{window_id} #{pane_id} -n pve-1 ",
		"tmux new-window -t netssh-pve-2: -P -F #{window_id} #{pane_id} -n pve-2 ",
	} {
		if !strings.Contains(joined, want) {
			t.Errorf("missing %q in\n%s", want, joined)
		}
	}
	if strings.Contains(joined, "synchronize-panes") {
		t.Error("sync set without --sync")
	}
	if strings.Join(f.exec, " ") != "tmux attach-session -t netssh-pve-2" || len(hints) != 1 {
		t.Fatalf("exec %v hints %v", f.exec, hints)
	}
}

func TestZellijOutsideWritesGridLayout(t *testing.T) {
	f := newFake(nil, "zellij")
	if err := Open(Zellij, panes("a", "b", "c", `q"x`), Options{Label: "pve", LayoutDir: "/tmp/l"}, f); err != nil {
		t.Fatal(err)
	}
	layout := f.files["/tmp/l/netssh-multi.kdl"]
	for _, want := range []string{
		`plugin location="zellij:tab-bar"`,
		`tab name="pve" focus=true {`,
		`pane split_direction="vertical" {`,
		`pane name="a" command="/usr/bin/netssh" {`,
		`args "a"`,
		`pane name="q\"x" command="/usr/bin/netssh" {`,
	} {
		if !strings.Contains(layout, want) {
			t.Errorf("layout lacks %q:\n%s", want, layout)
		}
	}
	// 4 panes → 2 columns × 2 rows.
	if n := strings.Count(layout, `split_direction="vertical"`); n != 2 {
		t.Errorf("%d rows, want 2:\n%s", n, layout)
	}
	if strings.Join(f.exec, " ") != "zellij --layout /tmp/l/netssh-multi.kdl" {
		t.Fatalf("exec %v", f.exec)
	}
}

func TestZellijInsideAddsTabs(t *testing.T) {
	f := newFake(map[string]string{"ZELLIJ": "0"}, "zellij")
	if err := Open(Zellij, panes("a", "b", "c"), Options{Label: "pve", PerWindow: 2, Sync: true, LayoutDir: "/tmp/l"}, f); err != nil {
		t.Fatal(err)
	}
	want := []string{
		"zellij action new-tab --layout /tmp/l/netssh-multi-1.kdl",
		"zellij action toggle-active-sync-tab",
		"zellij action new-tab --layout /tmp/l/netssh-multi-2.kdl",
		"zellij action toggle-active-sync-tab",
	}
	if strings.Join(f.calls, "\n") != strings.Join(want, "\n") {
		t.Fatalf("calls:\n%s", strings.Join(f.calls, "\n"))
	}
	if !strings.Contains(f.files["/tmp/l/netssh-multi-2.kdl"], `tab name="pve-2"`) {
		t.Fatalf("second tab: %s", f.files["/tmp/l/netssh-multi-2.kdl"])
	}
}

func TestToggleSync(t *testing.T) {
	f := newFake(map[string]string{"TMUX": "x"})
	if state, err := ToggleSync(f); err != nil || state != "broadcast on" || f.calls[1] != "tmux set-window-option synchronize-panes on" {
		t.Fatalf("%q %v %v", state, err, f.calls)
	}
	f.syncState = "on"
	if state, _ := ToggleSync(f); state != "broadcast off" {
		t.Fatalf("%q", state)
	}
	z := newFake(map[string]string{"ZELLIJ": "0"})
	if _, err := ToggleSync(z); err != nil || z.calls[0] != "zellij action toggle-active-sync-tab" {
		t.Fatalf("%v %v", err, z.calls)
	}
	if _, err := ToggleSync(newFake(nil)); err == nil {
		t.Fatal("outside a multiplexer accepted")
	}
}