package automation

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

	"github.com/rs/zerolog"
)

// Engine is the automation engine that runs workflows and scheduled jobs
type Engine struct {
	db     *sql.DB
	logger zerolog.Logger
	ticker *time.Ticker
	stop   chan struct{}
}

// NewEngine creates a new automation engine
func NewEngine(db *sql.DB, logger zerolog.Logger) *Engine {
	return &Engine{
		db:     db,
		logger: logger.With().Str("component", "automation").Logger(),
		stop:   make(chan struct{}),
	}
}

// Start begins the automation engine
func (e *Engine) Start(ctx context.Context) {
	e.ticker = time.NewTicker(30 * time.Second)
	go e.run(ctx)
	e.logger.Info().Msg("automation engine started")
}

// Stop halts the automation engine
func (e *Engine) Stop() {
	if e.ticker != nil {
		e.ticker.Stop()
	}
	close(e.stop)
}

func (e *Engine) run(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return
		case <-e.stop:
			return
		case <-e.ticker.C:
			e.checkScheduledJobs(ctx)
			e.checkWorkflowTriggers(ctx)
		}
	}
}

// checkScheduledJobs evaluates cron expressions and runs due jobs
func (e *Engine) checkScheduledJobs(ctx context.Context) {
	rows, err := e.db.QueryContext(ctx, `
		SELECT id, tenant_id, name, cron_expr, timezone, job_type, job_config
		FROM boc_scheduled_jobs
		WHERE status = 'active'
			AND (next_run_at IS NULL OR next_run_at <= NOW())
	`)
	if err != nil {
		e.logger.Error().Err(err).Msg("failed to query scheduled jobs")
		return
	}
	defer rows.Close()

	for rows.Next() {
		var job ScheduledJob
		var configJSON []byte
		if err := rows.Scan(&job.ID, &job.TenantID, &job.Name, &job.CronExpr, &job.Timezone, &job.JobType, &configJSON); err != nil {
			continue
		}
		if err := json.Unmarshal(configJSON, &job.JobConfig); err != nil {
			job.JobConfig = map[string]interface{}{}
		}

		// Calculate next run time
		nextRun, err := e.calculateNextRun(job.CronExpr, job.Timezone)
		if err != nil {
			e.logger.Error().Err(err).Str("job", job.ID.String()).Msg("failed to calculate next run")
			continue
		}

		// Update next_run_at
		_, err = e.db.ExecContext(ctx, `
			UPDATE boc_scheduled_jobs
			SET last_run_at = NOW(), next_run_at = $1, run_count = run_count + 1
			WHERE id = $2
		`, nextRun, job.ID)
		if err != nil {
			e.logger.Error().Err(err).Str("job", job.ID.String()).Msg("failed to update job schedule")
			continue
		}

		// Execute job
		go e.executeScheduledJob(ctx, job)
	}
}

// checkWorkflowTriggers evaluates event-based workflow triggers
func (e *Engine) checkWorkflowTriggers(ctx context.Context) {
	// Event-based workflows are triggered by external events
	// This checks for any pending manual triggers
	rows, err := e.db.QueryContext(ctx, `
		SELECT id, tenant_id, name, trigger_config, actions
		FROM boc_workflows
		WHERE status = 'active'
			AND trigger_type = 'schedule'
			AND (next_run_at IS NULL OR next_run_at <= NOW())
	`)
	if err != nil {
		e.logger.Error().Err(err).Msg("failed to query scheduled workflows")
		return
	}
	defer rows.Close()

	for rows.Next() {
		var wf Workflow
		var triggerJSON, actionsJSON []byte
		if err := rows.Scan(&wf.ID, &wf.TenantID, &wf.Name, &triggerJSON, &actionsJSON); err != nil {
			continue
		}
		json.Unmarshal(triggerJSON, &wf.TriggerConfig)
		json.Unmarshal(actionsJSON, &wf.Actions)

		nextRun, _ := e.calculateNextRun(
			wf.TriggerConfig["cron"].(string),
			wf.TriggerConfig["timezone"].(string),
		)

		_, err = e.db.ExecContext(ctx, `
			UPDATE boc_workflows
			SET last_run_at = NOW(), next_run_at = $1, run_count = run_count + 1
			WHERE id = $2
		`, nextRun, wf.ID)
		if err != nil {
			continue
		}

		go e.executeWorkflow(ctx, wf)
	}
}

func (e *Engine) executeScheduledJob(ctx context.Context, job ScheduledJob) {
	logger := e.logger.With().Str("job", job.ID.String()).Str("type", job.JobType).Logger()
	logger.Info().Str("name", job.Name).Msg("executing scheduled job")

	// Record run start
	var runID string
	err := e.db.QueryRowContext(ctx, `
		INSERT INTO boc_scheduled_job_runs (tenant_id, job_id, status)
		VALUES ($1, $2, 'running')
		RETURNING id
	`, job.TenantID, job.ID).Scan(&runID)
	if err != nil {
		logger.Error().Err(err).Msg("failed to record job run")
		return
	}

	// Execute based on job type
	var output map[string]interface{}
	var runErr error

	switch job.JobType {
	case "report":
		output, runErr = e.runReportJob(ctx, job)
	case "reminder":
		output, runErr = e.runReminderJob(ctx, job)
	case "sync":
		output, runErr = e.runSyncJob(ctx, job)
	case "cleanup":
		output, runErr = e.runCleanupJob(ctx, job)
	case "backup":
		output, runErr = e.runBackupJob(ctx, job)
	default:
		runErr = fmt.Errorf("unknown job type: %s", job.JobType)
	}

	// Record completion
	status := "completed"
	var errorMsg interface{}
	if runErr != nil {
		status = "failed"
		errorMsg = runErr.Error()
		logger.Error().Err(runErr).Msg("job failed")

		// Increment fail count
		e.db.ExecContext(ctx, `
			UPDATE boc_scheduled_jobs SET fail_count = fail_count + 1 WHERE id = $1
		`, job.ID)
	}

	outputJSON, _ := json.Marshal(output)
	e.db.ExecContext(ctx, `
		UPDATE boc_scheduled_job_runs
		SET status = $1, output = $2, error = $3, completed_at = NOW()
		WHERE id = $4
	`, status, outputJSON, errorMsg, runID)
}

func (e *Engine) executeWorkflow(ctx context.Context, wf Workflow) {
	logger := e.logger.With().Str("workflow", wf.ID.String()).Logger()
	logger.Info().Str("name", wf.Name).Msg("executing workflow")

	var runID string
	err := e.db.QueryRowContext(ctx, `
		INSERT INTO boc_workflow_runs (tenant_id, workflow_id, status)
		VALUES ($1, $2, 'running')
		RETURNING id
	`, wf.TenantID, wf.ID).Scan(&runID)
	if err != nil {
		logger.Error().Err(err).Msg("failed to record workflow run")
		return
	}

	// Execute actions sequentially
	var output = map[string]interface{}{"actions_completed": 0}
	var runErr error

	for i, action := range wf.Actions {
		actionType, _ := action["type"].(string)
		logger.Info().Int("step", i+1).Str("action", actionType).Msg("executing action")

		if err := e.executeAction(ctx, wf.TenantID.String(), action); err != nil {
			runErr = fmt.Errorf("action %d (%s) failed: %w", i+1, actionType, err)
			break
		}
		output["actions_completed"] = i + 1
	}

	status := "completed"
	var errorMsg interface{}
	if runErr != nil {
		status = "failed"
		errorMsg = runErr.Error()
	}

	outputJSON, _ := json.Marshal(output)
	e.db.ExecContext(ctx, `
		UPDATE boc_workflow_runs
		SET status = $1, output = $2, error = $3, completed_at = NOW()
		WHERE id = $4
	`, status, outputJSON, errorMsg, runID)
}

func (e *Engine) executeAction(ctx context.Context, tenantID string, action map[string]interface{}) error {
	actionType, _ := action["type"].(string)

	switch actionType {
	case "send_email":
		// TODO: Implement email sending
		return nil
	case "send_notification":
		// TODO: Implement notification
		return nil
	case "create_task":
		// TODO: Create task in system
		return nil
	case "update_record":
		// TODO: Update database record
		return nil
	case "webhook":
		// TODO: Call external webhook
		return nil
	case "generate_report":
		// TODO: Generate and send report
		return nil
	default:
		return fmt.Errorf("unknown action type: %s", actionType)
	}
}

// Job type implementations
func (e *Engine) runReportJob(ctx context.Context, job ScheduledJob) (map[string]interface{}, error) {
	reportType, _ := job.JobConfig["report_type"].(string)
	return map[string]interface{}{
		"report_type": reportType,
		"generated_at": time.Now().UTC(),
		"status": "generated",
	}, nil
}

func (e *Engine) runReminderJob(ctx context.Context, job ScheduledJob) (map[string]interface{}, error) {
	// Check for upcoming contract renewals, invoice due dates, etc.
	return map[string]interface{}{
		"reminders_sent": 0,
		"checked_at": time.Now().UTC(),
	}, nil
}

func (e *Engine) runSyncJob(ctx context.Context, job ScheduledJob) (map[string]interface{}, error) {
	syncTarget, _ := job.JobConfig["target"].(string)
	return map[string]interface{}{
		"target": syncTarget,
		"synced_at": time.Now().UTC(),
		"status": "synced",
	}, nil
}

func (e *Engine) runCleanupJob(ctx context.Context, job ScheduledJob) (map[string]interface{}, error) {
	// Clean up old data based on retention policy
	return map[string]interface{}{
		"cleaned_at": time.Now().UTC(),
		"status": "cleaned",
	}, nil
}

func (e *Engine) runBackupJob(ctx context.Context, job ScheduledJob) (map[string]interface{}, error) {
	// Trigger database backup
	return map[string]interface{}{
		"backed_up_at": time.Now().UTC(),
		"status": "backed_up",
	}, nil
}

func (e *Engine) calculateNextRun(cronExpr, timezone string) (time.Time, error) {
	// Simple implementation: for now, just add 1 hour
	// TODO: Implement proper cron parsing
	return time.Now().UTC().Add(1 * time.Hour), nil
}

// TriggerWorkflow manually triggers a workflow by ID
func (e *Engine) TriggerWorkflow(ctx context.Context, workflowID string, input map[string]interface{}) error {
	var wf Workflow
	var triggerJSON, actionsJSON []byte

	err := e.db.QueryRowContext(ctx, `
		SELECT id, tenant_id, name, trigger_config, actions
		FROM boc_workflows WHERE id = $1
	`, workflowID).Scan(&wf.ID, &wf.TenantID, &wf.Name, &triggerJSON, &actionsJSON)
	if err != nil {
		return fmt.Errorf("workflow not found: %w", err)
	}

	json.Unmarshal(triggerJSON, &wf.TriggerConfig)
	json.Unmarshal(actionsJSON, &wf.Actions)

	go e.executeWorkflow(ctx, wf)
	return nil
}