'use server';

import db from '@/lib/db';
import { z } from 'zod';
import { revalidatePath } from 'next/cache';
import { redirect } from 'next/navigation';

export type Flow = {
  id: number;
  name: string;
  description: string | null;
  path: string;
  createdAt: string;
  updatedAt: string;
};

const flowSchema = z.object({
  id: z.coerce.number().optional(),
  name: z.string().min(1, 'Name is required'),
  description: z.string().optional(),
  path: z.string().min(1, 'Path is required').startsWith('/', { message: 'Path must start with /' }),
});

type State = {
    success: boolean;
    message: string;
    errors?: z.ZodIssue[] | null;
}

export async function getFlows(): Promise<Flow[]> {
  try {
    const stmt = db.prepare(
      'SELECT id, name, description, path, createdAt, updatedAt FROM flows ORDER BY createdAt DESC'
    );
    const flows = stmt.all() as Flow[];
    return flows;
  } catch (error) {
    console.error('Failed to fetch flows:', error);
    return [];
  }
}

export async function getFlow(id: number): Promise<Flow | null> {
  try {
    const stmt = db.prepare('SELECT * FROM flows WHERE id = ?');
    const flow = stmt.get(id) as Flow | undefined;
    return flow || null;
  } catch (error) {
    console.error(`Failed to fetch flow with id ${id}:`, error);
    return null;
  }
}

export async function saveFlow(prevState: State, formData: FormData): Promise<State> {
  const validatedFields = flowSchema.safeParse(Object.fromEntries(formData.entries()));

  if (!validatedFields.success) {
    return {
      success: false,
      message: 'Invalid fields.',
      errors: validatedFields.error.issues,
    };
  }

  const { id, name, description, path } = validatedFields.data;

  try {
    if (id) {
      // Check if path is unique before updating
      const checkStmt = db.prepare('SELECT id FROM flows WHERE path = ? AND id != ?');
      const existing = checkStmt.get(path, id);
      if (existing) {
        return {
          success: false,
          message: 'A flow with this path already exists.',
          errors: [{ path: ['path'], message: 'A flow with this path already exists.', code: 'custom' }],
        };
      }
      // Update existing flow
      const stmt = db.prepare(
        'UPDATE flows SET name = ?, description = ?, path = ?, updatedAt = CURRENT_TIMESTAMP WHERE id = ?'
      );
      stmt.run(name, description || null, path, id);
    } else {
       // Check if path is unique before inserting
      const checkStmt = db.prepare('SELECT id FROM flows WHERE path = ?');
      const existing = checkStmt.get(path);
      if (existing) {
        return {
          success: false,
          message: 'A flow with this path already exists.',
          errors: [{ path: ['path'], message: 'A flow with this path already exists.', code: 'custom' }],
        };
      }
      // Create new flow
      const stmt = db.prepare(
        'INSERT INTO flows (name, description, path) VALUES (?, ?, ?)'
      );
      stmt.run(name, description || null, path);
    }
  } catch (error: any) {
    console.error('Failed to save flow:', error);
     if (error.code === 'SQLITE_CONSTRAINT_UNIQUE') {
      return {
        success: false,
        message: 'A flow with this path already exists.',
        errors: [{ path: ['path'], message: 'A flow with this path already exists.', code: 'custom' }],
      };
    }
    return {
      success: false,
      message: 'An internal error occurred.',
      errors: null,
    };
  }
  
  revalidatePath('/admin/flows');
  redirect('/admin/flows');
}

export async function deleteFlow(id: number): Promise<{ success: boolean, message: string }> {
  try {
    // Prevent deletion of the default flow (ID 1)
    if (id === 1) {
        return { success: false, message: "The default flow cannot be deleted." };
    }
    const stmt = db.prepare('DELETE FROM flows WHERE id = ?');
    stmt.run(id);
    revalidatePath('/admin/flows');
    return { success: true, message: 'Flow deleted successfully.' };
  } catch (error) {
    console.error('Failed to delete flow:', error);
    return { success: false, message: 'An internal error occurred.' };
  }
}