-- 046_views.sql
-- Purpose: Analytical / monitoring views for Phase 1.1.
--   - v_price_divergence    (Cross_Source_Matching sec 2.2 + 4.6) — cross-source price disagreement
--   - v_cross_source_health (Master Plan sec 8.4)                 — listing-level spread metrics
--   - v_data_quality        (Master Plan sec 8.1)                 — KPI dashboard rows
-- Dependencies: house_sources, listing_sources, houses, listings, house_placement_history.
-- All CREATE OR REPLACE — idempotent.

BEGIN;

-- ─────────────────────────────────────────────────────────────────
-- v_price_divergence — Cross_Source sec 2.2: 5%+ spread between sources for same canonical listing
-- ─────────────────────────────────────────────────────────────────
CREATE OR REPLACE VIEW v_price_divergence AS
SELECT
    listing_id,
    ARRAY_AGG(DISTINCT ext_source) AS sources,
    MAX(price_rub) - MIN(price_rub) AS price_spread,
    (MAX(price_rub) - MIN(price_rub))::float / NULLIF(MIN(price_rub), 0) * 100 AS spread_pct,
    COUNT(*) AS source_count
FROM listing_sources
WHERE price_rub IS NOT NULL
GROUP BY listing_id
HAVING (MAX(price_rub) - MIN(price_rub))::float / NULLIF(MIN(price_rub), 0) > 0.05;

COMMENT ON VIEW v_price_divergence IS
  'Listings with cross-source price spread > 5%. Used by quality monitor + manual review queue.';

-- ─────────────────────────────────────────────────────────────────
-- v_cross_source_health — Master Plan sec 8.4: listing-level spread breakdown
-- ─────────────────────────────────────────────────────────────────
CREATE OR REPLACE VIEW v_cross_source_health AS
SELECT
    listing_id,
    array_agg(ext_source ORDER BY price_rub)     AS sources,
    array_agg(price_rub  ORDER BY price_rub)     AS prices,
    max(price_rub) - min(price_rub)              AS spread,
    (max(price_rub) - min(price_rub))::float
        / NULLIF(min(price_rub), 0) * 100        AS spread_pct,
    count(*)                                     AS source_count
FROM listing_sources
WHERE price_rub IS NOT NULL
GROUP BY listing_id
HAVING count(*) >= 2;

COMMENT ON VIEW v_cross_source_health IS
  'Per-listing cross-source price aggregation. Alert if spread_pct > 15% on > 100 listings.';

-- ─────────────────────────────────────────────────────────────────
-- v_data_quality — Master Plan sec 8.1: single-row KPI snapshot
-- ─────────────────────────────────────────────────────────────────
CREATE OR REPLACE VIEW v_data_quality AS
WITH active_listings AS (
    SELECT * FROM listings WHERE is_active = true
)
SELECT
    (SELECT count(*) FROM houses)                                                  AS houses_total,
    (SELECT count(*) FROM houses h
       WHERE EXISTS (SELECT 1 FROM house_sources hs WHERE hs.house_id = h.id))      AS houses_with_source,
    (SELECT count(*) FROM houses h
       WHERE EXISTS (SELECT 1 FROM house_sources hs
                      WHERE hs.house_id = h.id AND hs.ext_source = 'avito'))        AS houses_with_avito,
    (SELECT count(*) FROM houses h
       WHERE EXISTS (SELECT 1 FROM house_sources hs
                      WHERE hs.house_id = h.id AND hs.ext_source LIKE 'cian%'))     AS houses_with_cian,
    (SELECT count(*) FROM houses h
       WHERE EXISTS (SELECT 1 FROM house_sources hs
                      WHERE hs.house_id = h.id AND hs.ext_source = 'yandex'))       AS houses_with_yandex,
    (SELECT count(*) FROM (
        SELECT house_id FROM house_sources GROUP BY house_id HAVING count(*) >= 2
    ) sub)                                                                          AS houses_2plus_sources,
    (SELECT count(*) FROM (
        SELECT house_id FROM house_sources GROUP BY house_id HAVING count(*) >= 3
    ) sub)                                                                          AS houses_3plus_sources,
    (SELECT count(*) FROM active_listings)                                         AS listings_active,
    (SELECT count(*) FROM (
        SELECT listing_id FROM listing_sources
         WHERE listing_id IN (SELECT id FROM active_listings)
         GROUP BY listing_id HAVING count(*) >= 2
    ) sub)                                                                          AS listings_dedup_2sources,
    (SELECT count(*) FROM active_listings WHERE lat IS NOT NULL) * 100.0
        / NULLIF((SELECT count(*) FROM active_listings), 0)                         AS pct_geocoded,
    (SELECT count(*) FROM active_listings WHERE kadastr_num IS NOT NULL) * 100.0
        / NULLIF((SELECT count(*) FROM active_listings), 0)                         AS pct_cadastr,
    (SELECT count(*) FROM active_listings WHERE description IS NOT NULL) * 100.0
        / NULLIF((SELECT count(*) FROM active_listings), 0)                         AS pct_description,
    (SELECT count(*) FROM active_listings l
       JOIN houses h ON h.id = l.house_id_fk
       WHERE h.year_built IS NOT NULL) * 100.0
        / NULLIF((SELECT count(*) FROM active_listings), 0)                         AS pct_year_built,
    NOW() - (SELECT max(scraped_at) FROM listings WHERE source = 'avito')           AS avito_last_scrape_ago,
    NOW() - (SELECT max(scraped_at) FROM listings WHERE source = 'cian')            AS cian_last_scrape_ago,
    NOW() - (SELECT max(scraped_at) FROM listings WHERE source = 'yandex')          AS yandex_last_scrape_ago,
    (SELECT count(*) FROM v_price_divergence)                                       AS price_disagreements_count,
    (SELECT count(*) FROM listings WHERE is_outlier = true)                         AS outliers_flagged;

COMMENT ON VIEW v_data_quality IS
  'KPI snapshot. Refreshed on-demand by /api/v1/admin/data-quality endpoint (Master Plan sec 8.1).';

COMMIT;