-- ==========================================
-- Chat Switchboard - Initial Schema
-- ==========================================
-- PostgreSQL migration for backend support

-- Enable UUID extension
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

-- Users table (optional, for multi-user support)
CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    email VARCHAR(255) UNIQUE,
    password_hash VARCHAR(255),
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- API configurations per user
CREATE TABLE api_configs (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    user_id UUID REFERENCES users(id) ON DELETE CASCADE,
    name VARCHAR(100) NOT NULL DEFAULT 'default',
    endpoint VARCHAR(500) NOT NULL,
    api_key_encrypted TEXT NOT NULL,
    is_default BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    UNIQUE(user_id, name)
);

-- User settings
CREATE TABLE user_settings (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    user_id UUID UNIQUE REFERENCES users(id) ON DELETE CASCADE,
    default_model VARCHAR(100) DEFAULT 'gpt-3.5-turbo',
    stream_responses BOOLEAN DEFAULT TRUE,
    show_thinking BOOLEAN DEFAULT TRUE,
    system_prompt TEXT,
    max_tokens INTEGER DEFAULT 4096,
    temperature DECIMAL(3,2) DEFAULT 0.7,
    top_p DECIMAL(3,2) DEFAULT 1.0,
    presence_penalty DECIMAL(3,2) DEFAULT 0.0,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Chats
CREATE TABLE chats (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    user_id UUID REFERENCES users(id) ON DELETE CASCADE,
    title VARCHAR(255) NOT NULL,
    model VARCHAR(100),
    api_config_id UUID REFERENCES api_configs(id) ON DELETE SET NULL,
    is_archived BOOLEAN DEFAULT FALSE,
    is_pinned BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Messages
CREATE TABLE messages (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    chat_id UUID NOT NULL REFERENCES chats(id) ON DELETE CASCADE,
    role VARCHAR(20) NOT NULL CHECK (role IN ('system', 'user', 'assistant')),
    content TEXT NOT NULL,
    model VARCHAR(100),
    tokens_used INTEGER,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Cached models per API config
CREATE TABLE cached_models (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    api_config_id UUID NOT NULL REFERENCES api_configs(id) ON DELETE CASCADE,
    model_id VARCHAR(100) NOT NULL,
    owned_by VARCHAR(100),
    cached_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    UNIQUE(api_config_id, model_id)
);

-- Indexes for performance
CREATE INDEX idx_chats_user_id ON chats(user_id);
CREATE INDEX idx_chats_updated_at ON chats(updated_at DESC);
CREATE INDEX idx_messages_chat_id ON messages(chat_id);
CREATE INDEX idx_messages_created_at ON messages(created_at);
CREATE INDEX idx_api_configs_user_id ON api_configs(user_id);

-- Updated at trigger function
CREATE OR REPLACE FUNCTION update_updated_at_column()
RETURNS TRIGGER AS $$
BEGIN
    NEW.updated_at = NOW();
    RETURN NEW;
END;
$$ language 'plpgsql';

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

CREATE TRIGGER update_api_configs_updated_at BEFORE UPDATE ON api_configs
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_user_settings_updated_at BEFORE UPDATE ON user_settings
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

CREATE TRIGGER update_chats_updated_at BEFORE UPDATE ON chats
    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();

-- View for chat list with message count
CREATE VIEW chat_list AS
SELECT 
    c.id,
    c.user_id,
    c.title,
    c.model,
    c.is_archived,
    c.is_pinned,
    c.created_at,
    c.updated_at,
    COUNT(m.id) as message_count,
    MAX(m.created_at) as last_message_at
FROM chats c
LEFT JOIN messages m ON m.chat_id = c.id
GROUP BY c.id;