package session

import (
	"context"
	"database/sql"
	"errors"
	"sync"
	"testing"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/capability/restrict"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/db"
)

// newTestManager opens a private in-memory SQLite handle and builds a manager
// over it. Each caller gets an isolated, non-shared database so parallel tests
// never contend.
func newTestManager(t *testing.T) (*SessionManager, *sql.DB) {
	t.Helper()
	ctx := context.Background()
	handle, err := db.Open(ctx, ":memory:", nil)
	if err != nil {
		t.Fatalf("db.Open(:memory:) = %v", err)
	}
	t.Cleanup(func() { _ = handle.Close() })

	m, err := New(ctx, handle, nil)
	if err != nil {
		t.Fatalf("New() = %v", err)
	}
	return m, handle
}

func TestGetOrCreateCreatesAndReuses(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()
	msg := directMsg("o-100")

	first, err := m.GetOrCreate(ctx, msg, testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate() = %v", err)
	}
	if first.SessionID == "" {
		t.Fatal("first SessionID empty")
	}
	if !first.Owner || !first.MemWritable {
		t.Fatalf("owner session Owner=%v MemWritable=%v, want true/true", first.Owner, first.MemWritable)
	}

	second, err := m.GetOrCreate(ctx, msg, testOwner())
	if err != nil {
		t.Fatalf("second GetOrCreate() = %v", err)
	}
	if second.SessionID != first.SessionID {
		t.Errorf("SessionID changed across calls: %q != %q", first.SessionID, second.SessionID)
	}
	if second.ChannelID != first.ChannelID {
		t.Errorf("ChannelID changed: %q != %q", first.ChannelID, second.ChannelID)
	}
}

func TestGetOrCreateDifferentChannelsDiffer(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()

	s1, err := m.GetOrCreate(ctx, directMsg("o-100"), testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate(sender1) = %v", err)
	}
	s2, err := m.GetOrCreate(ctx, directMsg("o-100"), testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate(sender2) = %v", err)
	}
	// Same real account maps to the same session, so the channel id must be the
	// same; a different account must differ.
	s3, err := m.GetOrCreate(ctx, directMsg("stranger-1"), testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate(stranger) = %v", err)
	}
	if s1.SessionID != s2.SessionID {
		t.Error("same account produced different sessions")
	}
	if s3.SessionID == s1.SessionID {
		t.Error("different account collided onto the same session")
	}
}

func TestGetOrCreateGroupIsolation(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()

	// Owner speaking in a group: isolated context, memory read-only.
	sess, err := m.GetOrCreate(ctx, groupMsg("o-100"), testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate(owner group) = %v", err)
	}
	if !sess.IsGroup {
		t.Error("group message not flagged IsGroup")
	}
	if !sess.Owner {
		t.Error("owner in group should still be Owner")
	}
	if sess.MemWritable {
		t.Error("group session must be read-only (MemWritable=false) even for owner")
	}
	if got := sess.Env(); got != restrict.ActorGroupMember {
		t.Errorf("Env() = %q, want group_member", got)
	}
}

func TestGetOrCreateStrangerIsolation(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()

	sess, err := m.GetOrCreate(ctx, directMsg("stranger-1"), testOwner())
	if err != nil {
		t.Fatalf("GetOrCreate(stranger) = %v", err)
	}
	if sess.Owner {
		t.Error("stranger marked Owner")
	}
	if sess.MemWritable {
		t.Error("stranger session must be read-only (MemWritable=false)")
	}
	if sess.IsGroup {
		t.Error("stranger direct message marked IsGroup")
	}
}

func TestGetOrCreatePersistenceAcrossManagers(t *testing.T) {
	t.Parallel()

	ctx := context.Background()
	handle, err := db.Open(ctx, ":memory:", nil)
	if err != nil {
		t.Fatalf("db.Open = %v", err)
	}
	t.Cleanup(func() { _ = handle.Close() })

	m1, err := New(ctx, handle, nil)
	if err != nil {
		t.Fatalf("New#1 = %v", err)
	}
	first, err := m1.GetOrCreate(ctx, directMsg("o-100"), testOwner())
	if err != nil {
		t.Fatalf("m1.GetOrCreate = %v", err)
	}

	// A brand-new manager over the same database must recover the same binding.
	m2, err := New(ctx, handle, nil)
	if err != nil {
		t.Fatalf("New#2 = %v", err)
	}
	second, err := m2.GetOrCreate(ctx, directMsg("o-100"), testOwner())
	if err != nil {
		t.Fatalf("m2.GetOrCreate = %v", err)
	}
	if second.SessionID != first.SessionID {
		t.Errorf("session binding lost across managers: %q != %q", first.SessionID, second.SessionID)
	}
}

func TestGetOrCreateConcurrent(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()
	msg := directMsg("o-100")

	const n = 20
	ids := make([]string, n)
	errs := make([]error, n)
	var wg sync.WaitGroup
	wg.Add(n)
	for i := 0; i < n; i++ {
		i := i
		go func() {
			defer wg.Done()
			sess, err := m.GetOrCreate(ctx, msg, testOwner())
			if err != nil {
				errs[i] = err
				return
			}
			ids[i] = sess.SessionID
		}()
	}
	wg.Wait()

	for i := 0; i < n; i++ {
		if errs[i] != nil {
			t.Fatalf("goroutine %d: GetOrCreate = %v", i, errs[i])
		}
		if ids[i] == "" {
			t.Fatalf("goroutine %d produced empty session id", i)
		}
		if ids[i] != ids[0] {
			t.Errorf("goroutine %d session id %q != %q", i, ids[i], ids[0])
		}
	}
}

func TestGetOrCreateInvalidChannel(t *testing.T) {
	t.Parallel()

	m, _ := newTestManager(t)
	ctx := context.Background()

	msg := adapter.UnifiedMessage{
		Platform:    "qq",
		ChannelType: adapter.ChannelDirect,
	}
	_, err := m.GetOrCreate(ctx, msg, testOwner())
	if !errors.Is(err, ErrInvalidChannel) {
		t.Fatalf("GetOrCreate(invalid) error = %v, want ErrInvalidChannel", err)
	}
}

func TestNewRejectsNilDB(t *testing.T) {
	t.Parallel()

	if _, err := New(context.Background(), nil, nil); !errors.Is(err, ErrNilDB) {
		t.Fatalf("New(nil db) error = %v, want ErrNilDB", err)
	}
}