package store

import (
	"database/sql"
	"errors"
	"path/filepath"
	"testing"
	"time"

	"task-dashboard/internal/models"

	_ "github.com/mattn/go-sqlite3"
)

// newNativeTasksTestStore creates a Store backed by a fresh temp sqlite DB
// with just the native_tasks table -- enough to exercise
// CompleteNativeTask/UncompleteNativeTask/RescheduleNativeTask without
// running the full migration set.
func newNativeTasksTestStore(t *testing.T) *Store {
	t.Helper()
	dbPath := filepath.Join(t.TempDir(), "test.db")
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { db.Close() })
	if _, err := db.Exec(`
		CREATE TABLE native_tasks (
			id TEXT PRIMARY KEY,
			content TEXT NOT NULL,
			description TEXT DEFAULT '',
			project_name TEXT DEFAULT '',
			project_id TEXT DEFAULT '',
			due_date DATETIME,
			priority INTEGER DEFAULT 1,
			completed BOOLEAN DEFAULT 0,
			labels TEXT DEFAULT '[]',
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			recurrence_freq TEXT DEFAULT '',
			recurrence_interval INTEGER DEFAULT 1,
			recurrence_weekdays TEXT DEFAULT '',
			recurrence_series_id TEXT DEFAULT '',
			next_occurrence_override TEXT DEFAULT ''
		)
	`); err != nil {
		t.Fatal(err)
	}
	if _, err := db.Exec(`INSERT INTO native_tasks (id, content) VALUES ('real-1', 'Real task')`); err != nil {
		t.Fatal(err)
	}
	return &Store{db: db}
}

// TestCompleteNativeTask_UnknownID_ReturnsErrNotFound proves the 2026-07-12
// fix: a plain UPDATE ... WHERE id = ? silently "succeeds" with a nil error
// when 0 rows match (this is how database/sql's Exec behaves for an UPDATE
// that matches nothing -- no error, just RowsAffected() == 0). Before this
// fix, CompleteNativeTask returned that nil error straight through, so a
// stale/wrong id from a caller (the Android widget, in the real incident
// this was found from) looked identical to a real completion: HTTP 200,
// nothing changed in the database.
func TestCompleteNativeTask_UnknownID_ReturnsErrNotFound(t *testing.T) {
	s := newNativeTasksTestStore(t)

	err := s.CompleteNativeTask("does-not-exist")
	if !errors.Is(err, ErrNativeTaskNotFound) {
		t.Fatalf("expected ErrNativeTaskNotFound, got %v", err)
	}
}

func TestCompleteNativeTask_RealID_Succeeds(t *testing.T) {
	s := newNativeTasksTestStore(t)

	if err := s.CompleteNativeTask("real-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	var completed bool
	if err := s.db.QueryRow(`SELECT completed FROM native_tasks WHERE id = 'real-1'`).Scan(&completed); err != nil {
		t.Fatal(err)
	}
	if !completed {
		t.Error("expected task to be marked completed")
	}
}

func TestUncompleteNativeTask_UnknownID_ReturnsErrNotFound(t *testing.T) {
	s := newNativeTasksTestStore(t)

	err := s.UncompleteNativeTask("does-not-exist")
	if !errors.Is(err, ErrNativeTaskNotFound) {
		t.Fatalf("expected ErrNativeTaskNotFound, got %v", err)
	}
}

func TestRescheduleNativeTask_UnknownID_ReturnsErrNotFound(t *testing.T) {
	s := newNativeTasksTestStore(t)

	err := s.RescheduleNativeTask("does-not-exist", time.Now())
	if !errors.Is(err, ErrNativeTaskNotFound) {
		t.Fatalf("expected ErrNativeTaskNotFound, got %v", err)
	}
}

func TestGetNativeTasks_ParsesRecurrenceFields(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_weekdays, recurrence_series_id, next_occurrence_override)
		VALUES ('rec-1', 'Recurring task', '2026-07-13', 'weekly', 2, '1,3,5', 'series-abc', '2026-07-27')
	`); err != nil {
		t.Fatal(err)
	}

	tasks, err := s.GetNativeTasks()
	if err != nil {
		t.Fatalf("GetNativeTasks: %v", err)
	}

	var found *models.Task
	for i := range tasks {
		if tasks[i].ID == "rec-1" {
			found = &tasks[i]
		}
	}
	if found == nil {
		t.Fatal("expected to find rec-1")
	}
	if found.RecurrenceFreq != "weekly" {
		t.Errorf("RecurrenceFreq = %q, want %q", found.RecurrenceFreq, "weekly")
	}
	if found.RecurrenceInterval != 2 {
		t.Errorf("RecurrenceInterval = %d, want 2", found.RecurrenceInterval)
	}
	if len(found.RecurrenceWeekdays) != 3 || found.RecurrenceWeekdays[0] != 1 || found.RecurrenceWeekdays[1] != 3 || found.RecurrenceWeekdays[2] != 5 {
		t.Errorf("RecurrenceWeekdays = %v, want [1 3 5]", found.RecurrenceWeekdays)
	}
	if found.RecurrenceSeriesID != "series-abc" {
		t.Errorf("RecurrenceSeriesID = %q, want %q", found.RecurrenceSeriesID, "series-abc")
	}
	if found.NextOccurrenceOverride == nil || found.NextOccurrenceOverride.Format("2006-01-02") != "2026-07-27" {
		t.Errorf("NextOccurrenceOverride = %v, want 2026-07-27", found.NextOccurrenceOverride)
	}
}

func TestGetNativeTasks_NonRecurringTask_HasEmptyRecurrenceFields(t *testing.T) {
	s := newNativeTasksTestStore(t)
	// "real-1" (inserted by newNativeTasksTestStore) has no recurrence columns set.
	tasks, err := s.GetNativeTasks()
	if err != nil {
		t.Fatalf("GetNativeTasks: %v", err)
	}
	var found *models.Task
	for i := range tasks {
		if tasks[i].ID == "real-1" {
			found = &tasks[i]
		}
	}
	if found == nil {
		t.Fatal("expected to find real-1")
	}
	if found.RecurrenceSeriesID != "" {
		t.Errorf("expected empty RecurrenceSeriesID for non-recurring task, got %q", found.RecurrenceSeriesID)
	}
	if found.RecurrenceWeekdays != nil {
		t.Errorf("expected nil RecurrenceWeekdays for non-recurring task, got %v", found.RecurrenceWeekdays)
	}
	if found.NextOccurrenceOverride != nil {
		t.Errorf("expected nil NextOccurrenceOverride for non-recurring task, got %v", found.NextOccurrenceOverride)
	}
}

func TestGetNativeTaskByID_UnknownID_ReturnsErrNotFound(t *testing.T) {
	s := newNativeTasksTestStore(t)

	_, err := s.GetNativeTaskByID("does-not-exist")
	if !errors.Is(err, ErrNativeTaskNotFound) {
		t.Fatalf("expected ErrNativeTaskNotFound, got %v", err)
	}
}

func TestGetNativeTaskByID_RealID_ReturnsTask(t *testing.T) {
	s := newNativeTasksTestStore(t)

	task, err := s.GetNativeTaskByID("real-1")
	if err != nil {
		t.Fatalf("GetNativeTaskByID: %v", err)
	}
	if task.Content != "Real task" {
		t.Errorf("Content = %q, want %q", task.Content, "Real task")
	}
}

func TestCompleteNativeTask_NonRecurring_JustCompletes(t *testing.T) {
	s := newNativeTasksTestStore(t)

	if err := s.CompleteNativeTask("real-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	tasks, err := s.db.Query(`SELECT id FROM native_tasks`)
	if err != nil {
		t.Fatal(err)
	}
	defer tasks.Close()
	count := 0
	for tasks.Next() {
		count++
	}
	if count != 1 {
		t.Errorf("expected exactly 1 row (no iteration created for a non-recurring task), got %d", count)
	}
}

func TestCompleteNativeTask_LatestInSeries_CreatesNextIteration(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}

	if err := s.CompleteNativeTask("rec-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	var completed bool
	if err := s.db.QueryRow(`SELECT completed FROM native_tasks WHERE id = 'rec-1'`).Scan(&completed); err != nil {
		t.Fatal(err)
	}
	if !completed {
		t.Error("expected rec-1 to be marked completed")
	}

	var nextCount int
	var nextDue string
	if err := s.db.QueryRow(`
		SELECT COUNT(*), COALESCE(MAX(due_date), '') FROM native_tasks
		WHERE recurrence_series_id = 'series-1' AND id != 'rec-1'
	`).Scan(&nextCount, &nextDue); err != nil {
		t.Fatal(err)
	}
	if nextCount != 1 {
		t.Fatalf("expected exactly 1 new iteration, got %d", nextCount)
	}
	if nextDue[:10] != "2026-07-20" {
		t.Errorf("next iteration due_date = %q, want 2026-07-20", nextDue)
	}
}

func TestCompleteNativeTask_UsesNextOccurrenceOverride(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id, next_occurrence_override)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1', '2026-08-01')
	`); err != nil {
		t.Fatal(err)
	}

	if err := s.CompleteNativeTask("rec-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	var nextDue string
	if err := s.db.QueryRow(`
		SELECT due_date FROM native_tasks WHERE recurrence_series_id = 'series-1' AND id != 'rec-1'
	`).Scan(&nextDue); err != nil {
		t.Fatal(err)
	}
	if nextDue[:10] != "2026-08-01" {
		t.Errorf("next iteration due_date = %q, want 2026-08-01 (the override)", nextDue)
	}
}

func TestCompleteNativeTask_AlreadySuperseded_DoesNotDoubleCreate(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	// Simulate the periodic due-check having already created the successor
	// before the user got around to completing rec-1.
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-2', 'Water plants', '2026-07-20', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}

	if err := s.CompleteNativeTask("rec-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	var count int
	if err := s.db.QueryRow(`SELECT COUNT(*) FROM native_tasks WHERE recurrence_series_id = 'series-1'`).Scan(&count); err != nil {
		t.Fatal(err)
	}
	if count != 2 {
		t.Errorf("expected still exactly 2 rows in the series (no double-create), got %d", count)
	}
}

func TestCreateNextIteration_ConcurrentGuard_SecondCallIsNoOp(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	old, err := s.GetNativeTaskByID("rec-1")
	if err != nil {
		t.Fatal(err)
	}

	// Simulate two concurrent triggers both computing from the same
	// snapshot of rec-1 and both attempting to create its successor.
	if err := s.CreateNextIteration(*old); err != nil {
		t.Fatalf("first CreateNextIteration: %v", err)
	}
	if err := s.CreateNextIteration(*old); err != nil {
		t.Fatalf("second CreateNextIteration (should be a safe no-op, not an error): %v", err)
	}

	var count int
	if err := s.db.QueryRow(`SELECT COUNT(*) FROM native_tasks WHERE recurrence_series_id = 'series-1' AND id != 'rec-1'`).Scan(&count); err != nil {
		t.Fatal(err)
	}
	if count != 1 {
		t.Errorf("expected exactly 1 successor row after two CreateNextIteration calls from the same snapshot, got %d", count)
	}
}

func TestSetTaskRecurrence_FirstTimeGeneratesSeriesID(t *testing.T) {
	s := newNativeTasksTestStore(t)

	if err := s.SetTaskRecurrence("real-1", "weekly", 1, []int{1, 3}); err != nil {
		t.Fatalf("SetTaskRecurrence: %v", err)
	}

	task, err := s.GetNativeTaskByID("real-1")
	if err != nil {
		t.Fatal(err)
	}
	if task.RecurrenceFreq != "weekly" {
		t.Errorf("RecurrenceFreq = %q, want weekly", task.RecurrenceFreq)
	}
	if task.RecurrenceSeriesID == "" {
		t.Error("expected a generated RecurrenceSeriesID, got empty string")
	}
	if len(task.RecurrenceWeekdays) != 2 || task.RecurrenceWeekdays[0] != 1 || task.RecurrenceWeekdays[1] != 3 {
		t.Errorf("RecurrenceWeekdays = %v, want [1 3]", task.RecurrenceWeekdays)
	}
}

func TestSetTaskRecurrence_ClearingKeepsSeriesID(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if err := s.SetTaskRecurrence("real-1", "weekly", 1, nil); err != nil {
		t.Fatal(err)
	}
	task, err := s.GetNativeTaskByID("real-1")
	if err != nil {
		t.Fatal(err)
	}
	seriesID := task.RecurrenceSeriesID

	if err := s.SetTaskRecurrence("real-1", "", 1, nil); err != nil {
		t.Fatalf("SetTaskRecurrence (clear): %v", err)
	}

	task, err = s.GetNativeTaskByID("real-1")
	if err != nil {
		t.Fatal(err)
	}
	if task.RecurrenceFreq != "" {
		t.Errorf("RecurrenceFreq = %q, want empty after clearing", task.RecurrenceFreq)
	}
	if task.RecurrenceSeriesID != seriesID {
		t.Errorf("RecurrenceSeriesID = %q, want unchanged %q after clearing", task.RecurrenceSeriesID, seriesID)
	}
}

func TestSetNextOccurrenceOverride_UnknownID_ReturnsErrNotFound(t *testing.T) {
	s := newNativeTasksTestStore(t)
	err := s.SetNextOccurrenceOverride("does-not-exist", time.Date(2026, 8, 1, 0, 0, 0, 0, time.UTC))
	if !errors.Is(err, ErrNativeTaskNotFound) {
		t.Fatalf("expected ErrNativeTaskNotFound, got %v", err)
	}
}

func TestAdvanceDueRecurringTasks_DueUncompleted_CreatesSuccessor(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	now := time.Date(2026, 7, 14, 0, 0, 0, 0, time.UTC) // one day after due, still uncompleted

	n, err := s.AdvanceDueRecurringTasks(now)
	if err != nil {
		t.Fatalf("AdvanceDueRecurringTasks: %v", err)
	}
	if n != 1 {
		t.Fatalf("expected 1 iteration created, got %d", n)
	}

	var completed bool
	if err := s.db.QueryRow(`SELECT completed FROM native_tasks WHERE id = 'rec-1'`).Scan(&completed); err != nil {
		t.Fatal(err)
	}
	if completed {
		t.Error("expected rec-1 to remain uncompleted -- due-date passing doesn't complete it, just spawns the successor")
	}

	var count int
	if err := s.db.QueryRow(`SELECT COUNT(*) FROM native_tasks WHERE recurrence_series_id = 'series-1'`).Scan(&count); err != nil {
		t.Fatal(err)
	}
	if count != 2 {
		t.Fatalf("expected 2 rows in the series (original + successor), got %d", count)
	}
}

func TestAdvanceDueRecurringTasks_NotYetDue_LeavesAlone(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	now := time.Date(2026, 7, 10, 0, 0, 0, 0, time.UTC) // before the due date

	n, err := s.AdvanceDueRecurringTasks(now)
	if err != nil {
		t.Fatalf("AdvanceDueRecurringTasks: %v", err)
	}
	if n != 0 {
		t.Errorf("expected 0 iterations created for a not-yet-due task, got %d", n)
	}
}

func TestAdvanceDueRecurringTasks_AlreadyHasSuccessor_SkipsIt(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id)
		VALUES ('rec-2', 'Water plants', '2026-07-20', 'weekly', 1, 'series-1')
	`); err != nil {
		t.Fatal(err)
	}
	now := time.Date(2026, 7, 21, 0, 0, 0, 0, time.UTC)

	n, err := s.AdvanceDueRecurringTasks(now)
	if err != nil {
		t.Fatalf("AdvanceDueRecurringTasks: %v", err)
	}
	if n != 1 {
		t.Fatalf("expected only rec-2 (the latest, now also due) to spawn a successor, got n=%d", n)
	}

	var count int
	if err := s.db.QueryRow(`SELECT COUNT(*) FROM native_tasks WHERE recurrence_series_id = 'series-1'`).Scan(&count); err != nil {
		t.Fatal(err)
	}
	if count != 3 {
		t.Fatalf("expected 3 rows total (rec-1, rec-2, and rec-2's new successor), got %d", count)
	}
}

func TestAdvanceDueRecurringTasks_NonRecurringTask_NeverTouched(t *testing.T) {
	s := newNativeTasksTestStore(t)
	// "real-1" (from newNativeTasksTestStore) has no due_date and no recurrence.
	now := time.Date(2026, 7, 14, 0, 0, 0, 0, time.UTC)

	n, err := s.AdvanceDueRecurringTasks(now)
	if err != nil {
		t.Fatalf("AdvanceDueRecurringTasks: %v", err)
	}
	if n != 0 {
		t.Errorf("expected 0 iterations created (no recurring tasks in fixture), got %d", n)
	}
}

func TestGetNativeTasks_ParsesProjectID(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`INSERT INTO native_tasks (id, content, project_id) VALUES ('proj-1', 'Task with project', 'project-abc')`); err != nil {
		t.Fatal(err)
	}

	tasks, err := s.GetNativeTasks()
	if err != nil {
		t.Fatalf("GetNativeTasks: %v", err)
	}
	var found *models.Task
	for i := range tasks {
		if tasks[i].ID == "proj-1" {
			found = &tasks[i]
		}
	}
	if found == nil {
		t.Fatal("expected to find proj-1")
	}
	if found.ProjectID != "project-abc" {
		t.Errorf("ProjectID = %q, want %q", found.ProjectID, "project-abc")
	}
}

func TestCreateNativeTask_PersistsProjectID(t *testing.T) {
	s := newNativeTasksTestStore(t)
	task := models.Task{ID: "new-1", Content: "New task", ProjectID: "project-xyz"}
	if err := s.CreateNativeTask(task); err != nil {
		t.Fatalf("CreateNativeTask: %v", err)
	}

	got, err := s.GetNativeTaskByID("new-1")
	if err != nil {
		t.Fatal(err)
	}
	if got.ProjectID != "project-xyz" {
		t.Errorf("ProjectID = %q, want %q", got.ProjectID, "project-xyz")
	}
}

func TestCreateNextIteration_InheritsProjectIDAndLabels(t *testing.T) {
	s := newNativeTasksTestStore(t)
	if _, err := s.db.Exec(`
		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_interval, recurrence_series_id, project_id, labels)
		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 1, 'series-1', 'project-abc', '["chore","garden"]')
	`); err != nil {
		t.Fatal(err)
	}

	if err := s.CompleteNativeTask("rec-1"); err != nil {
		t.Fatalf("CompleteNativeTask: %v", err)
	}

	var nextID string
	if err := s.db.QueryRow(`SELECT id FROM native_tasks WHERE recurrence_series_id = 'series-1' AND id != 'rec-1'`).Scan(&nextID); err != nil {
		t.Fatal(err)
	}
	next, err := s.GetNativeTaskByID(nextID)
	if err != nil {
		t.Fatal(err)
	}
	if next.ProjectID != "project-abc" {
		t.Errorf("next iteration ProjectID = %q, want %q", next.ProjectID, "project-abc")
	}
	if len(next.Labels) != 2 || next.Labels[0] != "chore" || next.Labels[1] != "garden" {
		t.Errorf("next iteration Labels = %v, want [chore garden]", next.Labels)
	}
}