-- Stonks Oracle - Trend evidence mappings
-- Links trend_windows to the documents that contributed as evidence,
-- storing the evidence type (supporting/opposing), rank score, and
-- weight breakdown for explainability and drill-down queries.
-- Requirements: 6.5, 10.4

CREATE TABLE trend_evidence (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    trend_window_id UUID NOT NULL REFERENCES trend_windows(id) ON DELETE CASCADE,
    document_id UUID NOT NULL,
    evidence_type VARCHAR(20) NOT NULL DEFAULT 'supporting',  -- supporting | opposing
    rank_score FLOAT DEFAULT 0.0,
    weight_component FLOAT DEFAULT 0.0,
    impact_component FLOAT DEFAULT 0.0,
    recency_component FLOAT DEFAULT 0.0,
    confidence_component FLOAT DEFAULT 0.0,
    sentiment_value FLOAT DEFAULT 0.0,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX idx_trend_evidence_trend ON trend_evidence(trend_window_id);
CREATE INDEX idx_trend_evidence_doc ON trend_evidence(document_id);
CREATE INDEX idx_trend_evidence_type ON trend_evidence(trend_window_id, evidence_type);