-- AI Recruitment Site Database Schema
-- Using PostgreSQL with proper indexing and constraints

-- Admins table
CREATE TABLE IF NOT EXISTS admins (
  id SERIAL PRIMARY KEY,
  email VARCHAR(255) UNIQUE NOT NULL,
  password_hash TEXT NOT NULL,
  full_name VARCHAR(255) NOT NULL,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
  last_login TIMESTAMP WITH TIME ZONE
);

-- Create index for faster email lookups
CREATE INDEX IF NOT EXISTS idx_admins_email ON admins(email);

-- Job postings table
CREATE TABLE IF NOT EXISTS job_postings (
  id SERIAL PRIMARY KEY,
  title VARCHAR(255) NOT NULL,
  department VARCHAR(100),
  location VARCHAR(255),
  employment_type VARCHAR(50), -- Full-time, Part-time, Contract
  salary_range VARCHAR(100),
  description TEXT NOT NULL,
  requirements TEXT,
  benefits TEXT,
  is_active BOOLEAN DEFAULT true,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
  created_by INTEGER REFERENCES admins(id)
);

-- Create index for active jobs
CREATE INDEX IF NOT EXISTS idx_job_postings_active ON job_postings(is_active, created_at DESC);

-- Applicants table
CREATE TABLE IF NOT EXISTS applicants (
  id SERIAL PRIMARY KEY,
  full_name VARCHAR(255) NOT NULL,
  email VARCHAR(255) NOT NULL,
  phone VARCHAR(50),
  linkedin_url VARCHAR(500),
  portfolio_url VARCHAR(500),
  years_of_experience INTEGER,
  current_position VARCHAR(255),
  current_company VARCHAR(255),
  preferred_location VARCHAR(255),
  created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

-- Create index for applicant searches
CREATE INDEX IF NOT EXISTS idx_applicants_email ON applicants(email);
CREATE INDEX IF NOT EXISTS idx_applicants_name ON applicants(full_name);
CREATE INDEX IF NOT EXISTS idx_applicants_created_at ON applicants(created_at DESC);

-- Applications table (links applicants to jobs with CV)
CREATE TABLE IF NOT EXISTS applications (
  id SERIAL PRIMARY KEY,
  applicant_id INTEGER NOT NULL REFERENCES applicants(id) ON DELETE CASCADE,
  job_id INTEGER REFERENCES job_postings(id) ON DELETE SET NULL,
  cover_letter TEXT,
  cv_filename VARCHAR(500),
  cv_content_type VARCHAR(100),
  cv_file BYTEA, -- Store CV as binary data
  status VARCHAR(50) DEFAULT 'new', -- new, reviewing, interview, rejected, hired
  notes TEXT,
  applied_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

-- Create indexes for application queries
CREATE INDEX IF NOT EXISTS idx_applications_applicant ON applications(applicant_id);
CREATE INDEX IF NOT EXISTS idx_applications_job ON applications(job_id);
CREATE INDEX IF NOT EXISTS idx_applications_status ON applications(status);
CREATE INDEX IF NOT EXISTS idx_applications_date ON applications(applied_at DESC);

-- Add check constraint for application status
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_constraint
    WHERE conname = 'applications_status_check'
  ) THEN
    ALTER TABLE applications ADD CONSTRAINT applications_status_check
    CHECK (status IN ('new', 'reviewing', 'interview', 'rejected', 'hired'));
  END IF;
END $$;

-- Add check constraint for employment type
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_constraint
    WHERE conname = 'job_postings_employment_type_check'
  ) THEN
    ALTER TABLE job_postings ADD CONSTRAINT job_postings_employment_type_check
    CHECK (employment_type IN ('Full-time', 'Part-time', 'Contract', 'Internship', 'Freelance'));
  END IF;
END $$;

-- Contact submissions table
CREATE TABLE IF NOT EXISTS contact_submissions (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  email VARCHAR(255) NOT NULL,
  subject VARCHAR(500),
  message TEXT NOT NULL,
  is_read BOOLEAN DEFAULT false,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

-- Create index for contact submissions
CREATE INDEX IF NOT EXISTS idx_contact_submissions_date ON contact_submissions(created_at DESC);
CREATE INDEX IF NOT EXISTS idx_contact_submissions_unread ON contact_submissions(is_read, created_at DESC);

-- Function to update the updated_at timestamp
CREATE OR REPLACE FUNCTION update_updated_at_column()
RETURNS TRIGGER AS $$
BEGIN
    NEW.updated_at = CURRENT_TIMESTAMP;
    RETURN NEW;
END;
$$ language 'plpgsql';

-- Trigger for job_postings
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_trigger WHERE tgname = 'update_job_postings_updated_at'
  ) THEN
    CREATE TRIGGER update_job_postings_updated_at
    BEFORE UPDATE ON job_postings
    FOR EACH ROW
    EXECUTE FUNCTION update_updated_at_column();
  END IF;
END $$;

-- Trigger for applications
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_trigger WHERE tgname = 'update_applications_updated_at'
  ) THEN
    CREATE TRIGGER update_applications_updated_at
    BEFORE UPDATE ON applications
    FOR EACH ROW
    EXECUTE FUNCTION update_updated_at_column();
  END IF;
END $$;