package sqlite

import (
	"context"
	"database/sql"
	"encoding/json"
	"time"

	"chat-switchboard/models"
	"chat-switchboard/store"
)

type TaskStore struct{}

func NewTaskStore() *TaskStore { return &TaskStore{} }

// ── Full column list (single source of truth) ──────────────────

// taskColumns is the canonical SELECT list for tasks.
// COALESCE wraps nullable columns that scan into non-pointer Go types.
// tool_grants uses COALESCE to '[]' so the string intermediate never sees NULL.
const taskColumns = `id, owner_id, team_id, name, description, scope,
	task_type, COALESCE(system_function, '') AS system_function,
	persona_id, model_id, system_prompt, user_prompt,
	workflow_id, COALESCE(tool_grants, '[]') AS tool_grants,
	schedule, timezone, is_active,
	COALESCE(trigger_token, '') AS trigger_token,
	max_tokens, max_tool_calls, max_wall_clock, output_mode,
	output_channel_id,
	COALESCE(webhook_url, '') AS webhook_url,
	COALESCE(webhook_secret, '') AS webhook_secret,
	provider_config_id,
	notify_on_complete, notify_on_failure,
	last_run_at, next_run_at, run_count, created_at, updated_at`

// scanTask scans a full task row into the model.
//
// SQLite dialect issues handled here:
//   - tool_grants: modernc driver returns TEXT as Go string, not []byte.
//     json.RawMessage (named []byte) can't accept string via convertAssign.
//     Scan into string intermediate, then cast.
//   - is_active, notify_on_complete, notify_on_failure: stored as INTEGER
//     (0/1). modernc returns int64, but convertAssign can't assign int64
//     to *bool. Scan into int intermediate, then convert.
//
// These match the patterns in store/sqlite/workflows.go.
func scanTask(scanner interface{ Scan(...interface{}) error }, t *models.Task) error {
	var toolGrantsStr string
	var isActive, notifyComplete, notifyFailure int
	err := scanner.Scan(
		&t.ID, &t.OwnerID, &t.TeamID, &t.Name, &t.Description, &t.Scope,
		&t.TaskType, &t.SystemFunction,
		&t.PersonaID, &t.ModelID, &t.SystemPrompt, &t.UserPrompt,
		&t.WorkflowID, &toolGrantsStr, &t.Schedule, &t.Timezone, &isActive,
		&t.TriggerToken,
		&t.MaxTokens, &t.MaxToolCalls, &t.MaxWallClock, &t.OutputMode,
		&t.OutputChannelID, &t.WebhookURL, &t.WebhookSecret, &t.ProviderConfigID,
		&notifyComplete, &notifyFailure,
		stN(&t.LastRunAt), stN(&t.NextRunAt), &t.RunCount, st(&t.CreatedAt), st(&t.UpdatedAt),
	)
	if err != nil {
		return err
	}
	t.ToolGrants = json.RawMessage(toolGrantsStr)
	t.IsActive = isActive != 0
	t.NotifyOnComplete = notifyComplete != 0
	t.NotifyOnFailure = notifyFailure != 0
	return nil
}

// ── CRUD ───────────────────────────────────────

func (s *TaskStore) Create(ctx context.Context, t *models.Task) error {
	t.ID = store.NewID()
	now := time.Now().UTC()
	t.CreatedAt = now
	t.UpdatedAt = now
	_, err := DB.ExecContext(ctx, `
		INSERT INTO tasks (id, owner_id, team_id, name, description, scope,
			task_type, system_function,
			persona_id, model_id, system_prompt, user_prompt,
			workflow_id, tool_grants, schedule, timezone, is_active,
			trigger_token,
			max_tokens, max_tool_calls, max_wall_clock, output_mode,
			output_channel_id, webhook_url, webhook_secret, provider_config_id,
			notify_on_complete, notify_on_failure, next_run_at)
		VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`,
		t.ID, t.OwnerID, t.TeamID, t.Name, t.Description, t.Scope,
		t.TaskType, t.SystemFunction,
		t.PersonaID, t.ModelID, t.SystemPrompt, t.UserPrompt,
		t.WorkflowID, nullableJSON(t.ToolGrants), t.Schedule, t.Timezone, boolToInt(t.IsActive),
		nilIfEmpty(t.TriggerToken),
		t.MaxTokens, t.MaxToolCalls, t.MaxWallClock, t.OutputMode,
		t.OutputChannelID, t.WebhookURL, t.WebhookSecret, t.ProviderConfigID,
		boolToInt(t.NotifyOnComplete), boolToInt(t.NotifyOnFailure), timeToSQLite(t.NextRunAt))
	return err
}

func (s *TaskStore) GetByID(ctx context.Context, id string) (*models.Task, error) {
	t := &models.Task{}
	row := DB.QueryRowContext(ctx, `SELECT `+taskColumns+` FROM tasks WHERE id = ?`, id)
	if err := scanTask(row, t); err != nil {
		return nil, err
	}
	return t, nil
}

func (s *TaskStore) GetByTriggerToken(ctx context.Context, token string) (*models.Task, error) {
	t := &models.Task{}
	row := DB.QueryRowContext(ctx, `SELECT `+taskColumns+` FROM tasks WHERE trigger_token = ?`, token)
	if err := scanTask(row, t); err != nil {
		return nil, err
	}
	return t, nil
}

func (s *TaskStore) Update(ctx context.Context, id string, p models.TaskPatch) error {
	q := "UPDATE tasks SET updated_at = datetime('now')"
	args := []interface{}{}
	if p.Name != nil { q += ", name = ?"; args = append(args, *p.Name) }
	if p.Description != nil { q += ", description = ?"; args = append(args, *p.Description) }
	if p.PersonaID != nil { q += ", persona_id = ?"; args = append(args, *p.PersonaID) }
	if p.ModelID != nil { q += ", model_id = ?"; args = append(args, *p.ModelID) }
	if p.SystemPrompt != nil { q += ", system_prompt = ?"; args = append(args, *p.SystemPrompt) }
	if p.UserPrompt != nil { q += ", user_prompt = ?"; args = append(args, *p.UserPrompt) }
	if p.WorkflowID != nil { q += ", workflow_id = ?"; args = append(args, *p.WorkflowID) }
	if p.ToolGrants != nil { q += ", tool_grants = ?"; args = append(args, nullableJSON(*p.ToolGrants)) }
	if p.Schedule != nil { q += ", schedule = ?"; args = append(args, *p.Schedule) }
	if p.Timezone != nil { q += ", timezone = ?"; args = append(args, *p.Timezone) }
	if p.IsActive != nil { q += ", is_active = ?"; args = append(args, boolToInt(*p.IsActive)) }
	if p.MaxTokens != nil { q += ", max_tokens = ?"; args = append(args, *p.MaxTokens) }
	if p.MaxToolCalls != nil { q += ", max_tool_calls = ?"; args = append(args, *p.MaxToolCalls) }
	if p.MaxWallClock != nil { q += ", max_wall_clock = ?"; args = append(args, *p.MaxWallClock) }
	if p.OutputMode != nil { q += ", output_mode = ?"; args = append(args, *p.OutputMode) }
	if p.OutputChannelID != nil { q += ", output_channel_id = ?"; args = append(args, *p.OutputChannelID) }
	if p.WebhookURL != nil { q += ", webhook_url = ?"; args = append(args, *p.WebhookURL) }
	if p.ProviderConfigID != nil { q += ", provider_config_id = ?"; args = append(args, *p.ProviderConfigID) }
	if p.NotifyOnComplete != nil { q += ", notify_on_complete = ?"; args = append(args, boolToInt(*p.NotifyOnComplete)) }
	if p.NotifyOnFailure != nil { q += ", notify_on_failure = ?"; args = append(args, boolToInt(*p.NotifyOnFailure)) }
	q += " WHERE id = ?"
	args = append(args, id)
	_, err := DB.ExecContext(ctx, q, args...)
	return err
}

func (s *TaskStore) Delete(ctx context.Context, id string) error {
	_, err := DB.ExecContext(ctx, `DELETE FROM tasks WHERE id = ?`, id)
	return err
}

func (s *TaskStore) ListByOwner(ctx context.Context, ownerID string) ([]models.Task, error) {
	return s.list(ctx, `WHERE owner_id = ? ORDER BY created_at DESC`, ownerID)
}

func (s *TaskStore) ListByTeam(ctx context.Context, teamID string) ([]models.Task, error) {
	return s.list(ctx, `WHERE team_id = ? ORDER BY created_at DESC`, teamID)
}

func (s *TaskStore) ListAll(ctx context.Context) ([]models.Task, error) {
	return s.list(ctx, `ORDER BY created_at DESC`)
}

func (s *TaskStore) ClaimDueTask(ctx context.Context) (*models.Task, error) {
	// SQLite: single-process, no contention. Select the oldest due task,
	// then atomically clear next_run_at to mark it claimed.
	t := &models.Task{}
	row := DB.QueryRowContext(ctx,
		`SELECT `+taskColumns+` FROM tasks
		 WHERE is_active = 1 AND next_run_at <= datetime('now')
		 ORDER BY next_run_at ASC LIMIT 1`)
	if err := scanTask(row, t); err != nil {
		return nil, err
	}
	_, _ = DB.ExecContext(ctx,
		`UPDATE tasks SET next_run_at = NULL WHERE id = ?`, t.ID)
	return t, nil
}

// ── Scheduler bookkeeping ──────────────────────

func (s *TaskStore) SetNextRun(ctx context.Context, id string, nextRun interface{}) error {
	_, err := DB.ExecContext(ctx, `UPDATE tasks SET next_run_at = ?, updated_at = datetime('now') WHERE id = ?`, timeToSQLiteAny(nextRun), id)
	return err
}

func (s *TaskStore) SetLastRun(ctx context.Context, id string) error {
	_, err := DB.ExecContext(ctx, `UPDATE tasks SET last_run_at = datetime('now'), updated_at = datetime('now') WHERE id = ?`, id)
	return err
}

func (s *TaskStore) IncrementRunCount(ctx context.Context, id string) error {
	_, err := DB.ExecContext(ctx, `UPDATE tasks SET run_count = run_count + 1, updated_at = datetime('now') WHERE id = ?`, id)
	return err
}

// ── Run History ─────────────────────────────────

func (s *TaskStore) CreateRun(ctx context.Context, r *models.TaskRun) error {
	r.ID = store.NewID()
	// F4 audit fix: set StartedAt in Go so the returned struct matches PG
	// behavior (PG returns it via RETURNING; SQLite can't).
	r.StartedAt = time.Now().UTC()
	_, err := DB.ExecContext(ctx, `
		INSERT INTO task_runs (id, task_id, channel_id, status, trigger_payload, started_at)
		VALUES (?, ?, ?, ?, ?, ?)`, r.ID, r.TaskID, r.ChannelID, r.Status,
		nilIfEmpty(r.TriggerPayload), r.StartedAt.UTC().Format("2006-01-02 15:04:05"))
	return err
}

func (s *TaskStore) CreateRunExclusive(ctx context.Context, taskID string) (*models.TaskRun, error) {
	// SQLite: check-then-insert. Single-process, no race.
	var count int
	err := DB.QueryRowContext(ctx, `
		SELECT COUNT(*) FROM task_runs
		WHERE task_id = ? AND status IN ('running', 'queued')`, taskID).Scan(&count)
	if err != nil {
		return nil, err
	}
	if count > 0 {
		return nil, sql.ErrNoRows
	}
	r := &models.TaskRun{
		ID:        store.NewID(),
		TaskID:    taskID,
		Status:    "running",
		StartedAt: time.Now().UTC(),
	}
	_, err = DB.ExecContext(ctx, `
		INSERT INTO task_runs (id, task_id, status, started_at)
		VALUES (?, ?, 'running', ?)`,
		r.ID, taskID, r.StartedAt.UTC().Format("2006-01-02 15:04:05"))
	if err != nil {
		return nil, err
	}
	return r, nil
}

func (s *TaskStore) UpdateRun(ctx context.Context, id, status string, tokensUsed, toolCalls, wallClock int, errMsg string) error {
	_, err := DB.ExecContext(ctx, `
		UPDATE task_runs SET status = ?, tokens_used = ?, tool_calls = ?,
			wall_clock = ?, error = ?, completed_at = datetime('now')
		WHERE id = ?`, status, tokensUsed, toolCalls, wallClock, errMsg, id)
	return err
}

func (s *TaskStore) TransitionRunStatus(ctx context.Context, id string, status string) error {
	_, err := DB.ExecContext(ctx, `UPDATE task_runs SET status = ? WHERE id = ?`, status, id)
	return err
}

func (s *TaskStore) GetActiveRun(ctx context.Context, taskID string) (*models.TaskRun, error) {
	r := &models.TaskRun{}
	err := DB.QueryRowContext(ctx, `
		SELECT id, task_id, channel_id, status, COALESCE(trigger_payload, ''), started_at
		FROM task_runs WHERE task_id = ? AND status = 'running'
		LIMIT 1`, taskID).Scan(&r.ID, &r.TaskID, &r.ChannelID, &r.Status, &r.TriggerPayload, st(&r.StartedAt))
	if err != nil {
		return nil, err
	}
	return r, nil
}

func (s *TaskStore) GetQueuedRun(ctx context.Context, taskID string) (*models.TaskRun, error) {
	r := &models.TaskRun{}
	err := DB.QueryRowContext(ctx, `
		SELECT id, task_id, channel_id, status, COALESCE(trigger_payload, ''), started_at
		FROM task_runs WHERE task_id = ? AND status = 'queued'
		ORDER BY started_at ASC LIMIT 1`, taskID).Scan(
		&r.ID, &r.TaskID, &r.ChannelID, &r.Status, &r.TriggerPayload, st(&r.StartedAt))
	if err != nil {
		return nil, err
	}
	return r, nil
}

func (s *TaskStore) ListRuns(ctx context.Context, taskID string, limit int) ([]models.TaskRun, error) {
	rows, err := DB.QueryContext(ctx, `
		SELECT id, task_id, channel_id, status, COALESCE(trigger_payload, ''),
			started_at, completed_at, tokens_used, tool_calls, wall_clock,
			COALESCE(error, '')
		FROM task_runs WHERE task_id = ?
		ORDER BY started_at DESC LIMIT ?`, taskID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var runs []models.TaskRun
	for rows.Next() {
		var r models.TaskRun
		if err := rows.Scan(&r.ID, &r.TaskID, &r.ChannelID, &r.Status, &r.TriggerPayload,
			st(&r.StartedAt), stN(&r.CompletedAt),
			&r.TokensUsed, &r.ToolCalls, &r.WallClock, &r.Error); err != nil {
			continue
		}
		runs = append(runs, r)
	}
	return runs, nil
}

// ── list helper ────────────────────────────────

func (s *TaskStore) list(ctx context.Context, where string, args ...interface{}) ([]models.Task, error) {
	q := `SELECT ` + taskColumns + ` FROM tasks ` + where

	rows, err := DB.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tasks []models.Task
	for rows.Next() {
		var t models.Task
		if err := scanTask(rows, &t); err != nil {
			continue
		}
		tasks = append(tasks, t)
	}
	return tasks, nil
}

// ── Helpers ─────────────────────────────────────

func nullableJSON(data []byte) interface{} {
	if len(data) == 0 || string(data) == "null" {
		return nil
	}
	return string(data)
}

func nilIfEmpty(s string) interface{} {
	if s == "" {
		return nil
	}
	return s
}

// timeToSQLite converts *time.Time to the TEXT format that datetime('now')
// produces ("2006-01-02 15:04:05"). Returns nil for nil input.
// This prevents the modernc driver from serializing time.Time in an
// unparseable format (int64 / RFC3339Nano / driver-specific).
func timeToSQLite(t *time.Time) interface{} {
	if t == nil {
		return nil
	}
	return t.UTC().Format("2006-01-02 15:04:05")
}

// timeToSQLiteAny handles interface{} that may be *time.Time, time.Time, or nil.
func timeToSQLiteAny(v interface{}) interface{} {
	if v == nil {
		return nil
	}
	switch t := v.(type) {
	case *time.Time:
		return timeToSQLite(t)
	case time.Time:
		return t.UTC().Format("2006-01-02 15:04:05")
	default:
		return v
	}
}
