-- Enable UUID extension for secure user identification
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

-- Create enum for skill levels
CREATE TYPE skill_level_enum AS ENUM ('never', 'not-autonomous', 'autonomous', 'expert');

-- Teams table
CREATE TABLE teams (
    id VARCHAR(50) PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    direction VARCHAR(100) NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Skill categories table
CREATE TABLE skill_categories (
    id VARCHAR(50) PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    icon VARCHAR(100) NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Skills table
CREATE TABLE skills (
    id VARCHAR(100) PRIMARY KEY,
    name VARCHAR(200) NOT NULL,
    description TEXT,
    icon VARCHAR(100),
    category_id VARCHAR(50) REFERENCES skill_categories(id),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Skill links table
CREATE TABLE skill_links (
    id SERIAL PRIMARY KEY,
    skill_id VARCHAR(100) REFERENCES skills(id) ON DELETE CASCADE,
    url TEXT NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Users table with UUID primary key for security
-- UUIDs prevent user enumeration attacks (vs sequential IDs 1,2,3...)
CREATE TABLE users (
    id SERIAL, -- Legacy ID kept for backward compatibility during migration
    uuid_id UUID DEFAULT uuid_generate_v4() NOT NULL,
    first_name VARCHAR(100) NOT NULL,
    last_name VARCHAR(100) NOT NULL,
    team_id VARCHAR(50) REFERENCES teams(id),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (uuid_id),
    UNIQUE(first_name, last_name, team_id),
    UNIQUE(uuid_id)
);

-- ========================================
-- SIMPLIFIED EVALUATION SCHEMA
-- ========================================

-- User evaluations - metadata about user's evaluation session
CREATE TABLE user_evaluations (
    id SERIAL PRIMARY KEY,
    user_id INTEGER, -- Legacy column kept for backward compatibility
    user_uuid UUID REFERENCES users(uuid_id) ON DELETE CASCADE,
    last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(user_uuid)
);

-- Skill evaluations - direct relationship between user and skill
CREATE TABLE skill_evaluations (
    id SERIAL PRIMARY KEY,
    user_evaluation_id INTEGER REFERENCES user_evaluations(id) ON DELETE CASCADE,
    skill_id VARCHAR(100) REFERENCES skills(id) ON DELETE CASCADE,
    level skill_level_enum NOT NULL,
    can_mentor BOOLEAN DEFAULT FALSE,
    wants_to_learn BOOLEAN DEFAULT FALSE,
    is_selected BOOLEAN DEFAULT TRUE, -- Replaces selected_skills table
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(user_evaluation_id, skill_id)
);

-- Insert initial teams data
INSERT INTO teams (id, name, direction) VALUES
    ('frontend', 'Frontend', 'Engineering'),
    ('backend', 'Backend', 'Engineering'),
    ('devops', 'DevOps', 'Engineering'),
    ('mobile', 'Mobile', 'Engineering'),
    ('data', 'Data Science', 'Engineering'),
    ('product', 'Product', 'Product'),
    ('design', 'Design', 'Product'),
    ('marketing', 'Marketing', 'Business');

-- Indexes for performance
CREATE INDEX idx_teams_direction ON teams(direction);
CREATE INDEX idx_skills_category_id ON skills(category_id);
CREATE INDEX idx_skill_links_skill_id ON skill_links(skill_id);
CREATE INDEX idx_users_team_id ON users(team_id);
CREATE INDEX idx_users_unique_person ON users(first_name, last_name, team_id);
CREATE INDEX idx_users_uuid_id ON users(uuid_id); -- Index on UUID for performance
CREATE INDEX idx_user_evaluations_user_uuid ON user_evaluations(user_uuid);
CREATE INDEX idx_user_evaluations_user_id ON user_evaluations(user_id); -- Legacy index
CREATE INDEX idx_skill_evaluations_user_evaluation_id ON skill_evaluations(user_evaluation_id);
CREATE INDEX idx_skill_evaluations_skill_id ON skill_evaluations(skill_id);
CREATE INDEX idx_skill_evaluations_is_selected ON skill_evaluations(is_selected);

-- Update trigger for users table
CREATE OR REPLACE FUNCTION update_updated_at_column()
RETURNS TRIGGER AS $$
BEGIN
    NEW.updated_at = CURRENT_TIMESTAMP;
    RETURN NEW;
END;
$$ language 'plpgsql';

CREATE TRIGGER update_teams_updated_at BEFORE UPDATE ON teams
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_skill_categories_updated_at BEFORE UPDATE ON skill_categories
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_skills_updated_at BEFORE UPDATE ON skills
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_users_updated_at BEFORE UPDATE ON users
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_skill_evaluations_updated_at BEFORE UPDATE ON skill_evaluations
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

-- Views for easy querying
CREATE VIEW user_skills_summary AS
SELECT 
    u.first_name,
    u.last_name,
    t.name as team_name,
    t.direction,
    sc.name as category_name,
    s.name as skill_name,
    se.level,
    se.can_mentor,
    se.wants_to_learn,
    se.is_selected,
    se.updated_at
FROM users u
JOIN teams t ON u.team_id = t.id
JOIN user_evaluations ue ON u.uuid_id = ue.user_uuid
JOIN skill_evaluations se ON ue.id = se.user_evaluation_id
JOIN skills s ON se.skill_id = s.id
JOIN skill_categories sc ON s.category_id = sc.id;

CREATE VIEW category_skills_count AS
SELECT 
    sc.id as category_id,
    sc.name as category_name,
    COUNT(s.id) as total_skills
FROM skill_categories sc
LEFT JOIN skills s ON sc.id = s.category_id
GROUP BY sc.id, sc.name;