CREATE TABLE incidents (
    id uuid PRIMARY KEY,
    correlation_key text NOT NULL CHECK (char_length(correlation_key) BETWEEN 1 AND 255),
    title text NOT NULL CHECK (char_length(title) BETWEEN 1 AND 240),
    summary text NOT NULL DEFAULT '' CHECK (char_length(summary) <= 2000),
    severity text NOT NULL CHECK (severity IN ('attention', 'degraded', 'critical')),
    status text NOT NULL DEFAULT 'open' CHECK (status IN ('open', 'acknowledged', 'resolved')),
    started_at timestamptz NOT NULL,
    resolved_at timestamptz,
    owner_user_id uuid REFERENCES users(id) ON DELETE SET NULL,
    correlation_method text NOT NULL CHECK (char_length(correlation_method) BETWEEN 1 AND 80),
    confidence numeric(4,3) NOT NULL CHECK (confidence >= 0 AND confidence <= 1),
    revision bigint NOT NULL DEFAULT 1 CHECK (revision > 0),
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now(),
    CHECK (status <> 'resolved' OR resolved_at IS NOT NULL),
    CHECK (status = 'resolved' OR resolved_at IS NULL)
);

CREATE UNIQUE INDEX incidents_active_correlation_key_uq ON incidents (correlation_key) WHERE status <> 'resolved';
CREATE INDEX incidents_list_idx ON incidents (status, severity, updated_at DESC, id ASC);
CREATE INDEX incidents_correlation_idx ON incidents (correlation_key, updated_at DESC, id ASC);

CREATE TABLE incident_alerts (
    incident_id uuid NOT NULL REFERENCES incidents(id) ON DELETE CASCADE,
    alert_id uuid NOT NULL REFERENCES alert_instances(id) ON DELETE RESTRICT,
    rationale text NOT NULL CHECK (char_length(rationale) BETWEEN 1 AND 500),
    confidence numeric(4,3) NOT NULL CHECK (confidence >= 0 AND confidence <= 1),
    correlation_method text NOT NULL CHECK (char_length(correlation_method) BETWEEN 1 AND 80),
    is_manual boolean NOT NULL DEFAULT false,
    added_by text NOT NULL DEFAULT '' CHECK (char_length(added_by) <= 160),
    created_at timestamptz NOT NULL DEFAULT now(),
    PRIMARY KEY (incident_id, alert_id)
);

CREATE INDEX incident_alerts_alert_idx ON incident_alerts (alert_id, incident_id);
CREATE INDEX incident_alerts_incident_idx ON incident_alerts (incident_id, created_at ASC, alert_id ASC);

CREATE TABLE incident_entities (
    incident_id uuid NOT NULL REFERENCES incidents(id) ON DELETE CASCADE,
    entity_id uuid NOT NULL REFERENCES entities(id) ON DELETE RESTRICT,
    rationale text NOT NULL CHECK (char_length(rationale) BETWEEN 1 AND 500),
    confidence numeric(4,3) NOT NULL CHECK (confidence >= 0 AND confidence <= 1),
    created_at timestamptz NOT NULL DEFAULT now(),
    PRIMARY KEY (incident_id, entity_id)
);

CREATE INDEX incident_entities_entity_idx ON incident_entities (entity_id, incident_id);