package statusfile

import (
	"context"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"antidrift/internal/domain"
	"antidrift/internal/session"
)

func activeState(deadline int64, driftStatus, nudge string) session.State {
	st := session.State{
		RuntimeState: domain.RuntimeActive,
		Commitment:   &session.CommitmentView{DeadlineUnixSecs: deadline},
	}
	if driftStatus != "" || nudge != "" {
		st.Drift = &session.DriftView{Status: driftStatus, Nudge: nudge}
	}
	return st
}

func TestRender(t *testing.T) {
	now := time.Unix(1_000_000, 0)
	in24m := now.Add(24 * time.Minute).Unix()

	cases := []struct {
		name string
		st   session.State
		want string
	}{
		{"locked", session.State{RuntimeState: domain.RuntimeLocked}, ""},
		{"empty runtime", session.State{}, ""},
		{"planning", session.State{RuntimeState: domain.RuntimePlanning}, "◔ planning"},
		{"review", session.State{RuntimeState: domain.RuntimeReview}, "✓ review"},
		{"active ontask", activeState(in24m, "ontask", ""), "● 24m"},
		{"active no drift view", activeState(in24m, "", ""), "● 24m"},
		{"active drifting", activeState(in24m, "drifting", ""), "⚠ DRIFT 24m"},
		{"active nudge", activeState(in24m, "ontask", "wandered off"), "● 24m ·?"},
		{"drift outranks nudge", activeState(in24m, "drifting", "wandered off"), "⚠ DRIFT 24m"},
		{"active no deadline", session.State{RuntimeState: domain.RuntimeActive}, "● 0m"},
		{"active past deadline", activeState(now.Add(-5*time.Minute).Unix(), "ontask", ""), "● 0m"},
		{"active partial minute rounds up", activeState(now.Add(10*time.Second).Unix(), "ontask", ""), "● 1m"},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			if got := Render(tc.st, now); got != tc.want {
				t.Errorf("Render() = %q, want %q", got, tc.want)
			}
		})
	}
}

func TestWriterWritesAndDedups(t *testing.T) {
	path := filepath.Join(t.TempDir(), "status")
	now := time.Unix(1_000_000, 0)
	state := session.State{RuntimeState: domain.RuntimePlanning}
	w := NewWriter(path, func() session.State { return state })
	w.now = func() time.Time { return now }

	w.write()
	if got := readFile(t, path); got != "◔ planning" {
		t.Fatalf("first write = %q", got)
	}

	// Same state: file untouched. Detect by clearing it and confirming the
	// deduped write does not recreate content.
	if err := os.WriteFile(path, []byte("sentinel"), 0o644); err != nil {
		t.Fatal(err)
	}
	w.write()
	if got := readFile(t, path); got != "sentinel" {
		t.Errorf("deduped write should not rewrite, got %q", got)
	}

	// Changed state: rewrites.
	state = session.State{RuntimeState: domain.RuntimeLocked}
	w.write()
	if got := readFile(t, path); got != "" {
		t.Errorf("changed write = %q, want empty", got)
	}
}

func TestWriterRemovesFileOnCancel(t *testing.T) {
	path := filepath.Join(t.TempDir(), "status")
	w := NewWriter(path, func() session.State {
		return session.State{RuntimeState: domain.RuntimePlanning}
	})
	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan struct{})
	go func() { w.Run(ctx); close(done) }()

	// Wait for the immediate write.
	waitFor(t, func() bool { _, err := os.Stat(path); return err == nil })
	cancel()
	<-done
	if _, err := os.Stat(path); !os.IsNotExist(err) {
		t.Errorf("file should be removed on cancel, stat err = %v", err)
	}
}

// Wake makes the writer re-render on a state change instead of waiting for the
// coarse minute tick, so the status bar tracks drift transitions promptly
// instead of lagging the web UI by up to a minute.
func TestWriterWakeRendersPromptly(t *testing.T) {
	path := filepath.Join(t.TempDir(), "status")
	now := time.Unix(1_000_000, 0)
	in10m := now.Add(10 * time.Minute).Unix()

	var mu sync.Mutex
	st := activeState(in10m, "ontask", "")
	w := NewWriter(path, func() session.State { mu.Lock(); defer mu.Unlock(); return st })
	w.now = func() time.Time { return now }

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	go w.Run(ctx)

	waitFor(t, func() bool { return fileEquals(path, "● 10m") })

	mu.Lock()
	st = activeState(in10m, "drifting", "")
	mu.Unlock()
	w.Wake()

	waitFor(t, func() bool { return fileEquals(path, "⚠ DRIFT 10m") })
}

func fileEquals(path, want string) bool {
	b, err := os.ReadFile(path)
	return err == nil && string(b) == want
}

func readFile(t *testing.T, path string) string {
	t.Helper()
	b, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	return string(b)
}

func waitFor(t *testing.T, cond func() bool) {
	t.Helper()
	deadline := time.Now().Add(2 * time.Second)
	for time.Now().Before(deadline) {
		if cond() {
			return
		}
		time.Sleep(5 * time.Millisecond)
	}
	t.Fatal("condition not met within timeout")
}