-- Migration: 018_chat_histories
-- Adds a dedicated table for saving and retrieving agent chat histories.

CREATE TABLE IF NOT EXISTS chat_histories (
    id          UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
    session_id  TEXT        NOT NULL,
    title       TEXT,
    channel     TEXT,
    agent_id    TEXT,
    project_id  UUID        REFERENCES projects(guid) ON DELETE SET NULL,
    messages    JSONB       NOT NULL DEFAULT '[]',
    summary     TEXT,
    metadata    JSONB       NOT NULL DEFAULT '{}',
    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX IF NOT EXISTS idx_chat_histories_session_id ON chat_histories(session_id);
CREATE INDEX IF NOT EXISTS idx_chat_histories_project_id ON chat_histories(project_id) WHERE project_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_chat_histories_channel    ON chat_histories(channel)    WHERE channel IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_chat_histories_agent_id   ON chat_histories(agent_id)   WHERE agent_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_chat_histories_created_at ON chat_histories(created_at DESC);

CREATE INDEX IF NOT EXISTS idx_chat_histories_fts
    ON chat_histories
    USING GIN (to_tsvector('simple', coalesce(title, '') || ' ' || coalesce(summary, '')));