-- PostgreSQL schema for Fetch ML job persistence
-- Complements Redis for task queuing

CREATE TABLE IF NOT EXISTS jobs (
    id TEXT PRIMARY KEY,
    job_name TEXT NOT NULL,
    args TEXT,
    status TEXT NOT NULL DEFAULT 'pending',
    priority INTEGER DEFAULT 0,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
    started_at TIMESTAMP WITH TIME ZONE,
    ended_at TIMESTAMP WITH TIME ZONE,
    worker_id TEXT,
    error TEXT,
    datasets TEXT, -- JSON array
    metadata TEXT, -- JSON object
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS job_metrics (
    job_id TEXT,
    metric_name TEXT,
    metric_value TEXT,
    timestamp TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (job_id, metric_name, timestamp),
    FOREIGN KEY (job_id) REFERENCES jobs(id) ON DELETE CASCADE
);

CREATE TABLE IF NOT EXISTS workers (
    id TEXT PRIMARY KEY,
    hostname TEXT,
    last_heartbeat TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
    status TEXT DEFAULT 'active',
    current_jobs INTEGER DEFAULT 0,
    max_jobs INTEGER DEFAULT 1,
    metadata TEXT -- JSON object
);

CREATE TABLE IF NOT EXISTS system_metrics (
    metric_name TEXT,
    metric_value TEXT,
    timestamp TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (metric_name, timestamp)
);

-- Indexes for performance
CREATE INDEX IF NOT EXISTS idx_jobs_status ON jobs(status);
CREATE INDEX IF NOT EXISTS idx_jobs_created_at ON jobs(created_at);
CREATE INDEX IF NOT EXISTS idx_jobs_worker_id ON jobs(worker_id);
CREATE INDEX IF NOT EXISTS idx_job_metrics_job_id ON job_metrics(job_id);
CREATE INDEX IF NOT EXISTS idx_job_metrics_timestamp ON job_metrics(timestamp);
CREATE INDEX IF NOT EXISTS idx_workers_heartbeat ON workers(last_heartbeat);
CREATE INDEX IF NOT EXISTS idx_system_metrics_timestamp ON system_metrics(timestamp);

-- Function to update 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 to update timestamps
CREATE TRIGGER update_jobs_timestamp 
    BEFORE UPDATE ON jobs
    FOR EACH ROW
    EXECUTE FUNCTION update_updated_at_column();