-- Channels: user-defined broadcast channels with their schedule template
CREATE TABLE IF NOT EXISTS channels (
    id              TEXT PRIMARY KEY NOT NULL,
    owner_id        TEXT NOT NULL,
    name            TEXT NOT NULL,
    description     TEXT,
    timezone        TEXT NOT NULL DEFAULT 'UTC',
    -- JSON-encoded ScheduleConfig (the shareable/exportable template)
    schedule_config TEXT NOT NULL DEFAULT '{"blocks":[]}',
    -- JSON-encoded RecyclePolicy
    recycle_policy  TEXT NOT NULL DEFAULT '{"cooldown_days":30,"cooldown_generations":null,"min_available_ratio":0.2}',
    created_at      TEXT NOT NULL,
    updated_at      TEXT NOT NULL
);

CREATE INDEX IF NOT EXISTS idx_channels_owner ON channels(owner_id);

-- Generated 48-hour schedules (resolved from a channel's template)
CREATE TABLE IF NOT EXISTS generated_schedules (
    id          TEXT    PRIMARY KEY NOT NULL,
    channel_id  TEXT    NOT NULL,
    valid_from  TEXT    NOT NULL,
    valid_until TEXT    NOT NULL,
    generation  INTEGER NOT NULL,
    FOREIGN KEY (channel_id) REFERENCES channels(id) ON DELETE CASCADE
);

-- Composite index supports both "find active at time T" and "find latest"
CREATE INDEX IF NOT EXISTS idx_schedules_channel_valid
    ON generated_schedules(channel_id, valid_from DESC);

-- Individual scheduled slots within a generated schedule.
-- The MediaItem snapshot is stored as JSON so the EPG survives library changes.
CREATE TABLE IF NOT EXISTS scheduled_slots (
    id              TEXT PRIMARY KEY NOT NULL,
    schedule_id     TEXT NOT NULL,
    start_at        TEXT NOT NULL,
    end_at          TEXT NOT NULL,
    -- JSON-encoded MediaItem (metadata snapshot at generation time)
    item            TEXT NOT NULL,
    source_block_id TEXT NOT NULL,
    FOREIGN KEY (schedule_id) REFERENCES generated_schedules(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_slots_schedule_start
    ON scheduled_slots(schedule_id, start_at);

-- Playback history for the recycle policy engine
CREATE TABLE IF NOT EXISTS playback_records (
    id          TEXT    PRIMARY KEY NOT NULL,
    channel_id  TEXT    NOT NULL,
    item_id     TEXT    NOT NULL,
    played_at   TEXT    NOT NULL,
    generation  INTEGER NOT NULL,
    FOREIGN KEY (channel_id) REFERENCES channels(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_playback_channel_date
    ON playback_records(channel_id, played_at DESC);