-- Enable PostGIS
CREATE EXTENSION IF NOT EXISTS postgis;
CREATE EXTENSION IF NOT EXISTS postgis_topology;
CREATE EXTENSION IF NOT EXISTS pg_trgm;

-- ─── Cities ──────────────────────────────────────────────────────────────────

CREATE TABLE IF NOT EXISTS cities (
  slug          TEXT PRIMARY KEY,
  name          TEXT NOT NULL,
  country_code  CHAR(2) NOT NULL DEFAULT '',
  geofabrik_url TEXT NOT NULL,
  bbox          geometry(Polygon, 4326),
  resolution_m  INTEGER NOT NULL DEFAULT 200,
  status        TEXT NOT NULL DEFAULT 'empty'
                  CHECK (status IN ('empty','pending','processing','ready','error')),
  error_message TEXT,
  last_ingested TIMESTAMPTZ,
  created_at    TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- Migration for existing databases
ALTER TABLE cities ADD COLUMN IF NOT EXISTS resolution_m INTEGER NOT NULL DEFAULT 200;

CREATE INDEX IF NOT EXISTS idx_cities_bbox ON cities USING GIST (bbox);

-- ─── Raw POIs (created and managed by osm2pgsql flex output) ─────────────────
-- osm2pgsql --drop recreates this table on each ingest using the Lua script.
-- Columns: osm_id (bigint), osm_type (char), city_slug, category, subcategory,
--          name, tags, geom — no auto-generated id column.
-- This CREATE TABLE IF NOT EXISTS is a no-op after the first osm2pgsql run.

CREATE TABLE IF NOT EXISTS raw_pois (
  osm_id      BIGINT NOT NULL,
  osm_type    CHAR(1) NOT NULL,
  city_slug   TEXT NOT NULL,
  category    TEXT NOT NULL,
  subcategory TEXT NOT NULL,
  name        TEXT,
  tags        JSONB,
  geom        geometry(Point, 4326) NOT NULL
);

CREATE INDEX IF NOT EXISTS idx_raw_pois_city_cat
  ON raw_pois (city_slug, category);
CREATE INDEX IF NOT EXISTS idx_raw_pois_geom
  ON raw_pois USING GIST (geom);
CREATE INDEX IF NOT EXISTS idx_raw_pois_name
  ON raw_pois USING GIN (name gin_trgm_ops)
  WHERE name IS NOT NULL;

-- ─── Grid points ─────────────────────────────────────────────────────────────

CREATE TABLE IF NOT EXISTS grid_points (
  id        BIGSERIAL PRIMARY KEY,
  city_slug TEXT NOT NULL REFERENCES cities(slug) ON DELETE CASCADE,
  geom      geometry(Point, 4326) NOT NULL,
  grid_x    INTEGER NOT NULL,
  grid_y    INTEGER NOT NULL,
  UNIQUE (city_slug, grid_x, grid_y)
);

CREATE INDEX IF NOT EXISTS idx_grid_city  ON grid_points (city_slug);
CREATE INDEX IF NOT EXISTS idx_grid_geom  ON grid_points USING GIST (geom);

-- ─── Pre-computed accessibility scores ───────────────────────────────────────

CREATE TABLE IF NOT EXISTS grid_scores (
  grid_point_id BIGINT  NOT NULL REFERENCES grid_points(id) ON DELETE CASCADE,
  category      TEXT    NOT NULL,
  travel_mode   TEXT    NOT NULL CHECK (travel_mode IN ('walking','cycling','driving')),
  threshold_min INTEGER NOT NULL,
  profile       TEXT    NOT NULL DEFAULT 'universal',
  nearest_poi_id BIGINT,
  distance_m    FLOAT,
  travel_time_s FLOAT,
  score         FLOAT   NOT NULL CHECK (score >= 0 AND score <= 1),
  computed_at   TIMESTAMPTZ NOT NULL DEFAULT now(),
  PRIMARY KEY (grid_point_id, category, travel_mode, threshold_min, profile)
);

-- Migration for existing databases (adds profile column and rebuilds PK)
ALTER TABLE grid_scores ADD COLUMN IF NOT EXISTS profile TEXT NOT NULL DEFAULT 'universal';

CREATE INDEX IF NOT EXISTS idx_grid_scores_lookup
  ON grid_scores (grid_point_id, travel_mode, threshold_min, profile);

-- ─── Nearest POI per subcategory per grid point ───────────────────────────────
-- Populated by compute-scores job. Stores the nearest (by routing time) POI for
-- each subcategory at each grid point, for each travel mode. Threshold-independent.

CREATE TABLE IF NOT EXISTS grid_poi_details (
  grid_point_id    BIGINT NOT NULL REFERENCES grid_points(id) ON DELETE CASCADE,
  category         TEXT NOT NULL,
  subcategory      TEXT NOT NULL,
  travel_mode      TEXT NOT NULL,
  nearest_poi_id   BIGINT,
  nearest_poi_name TEXT,
  distance_m       FLOAT,
  travel_time_s    FLOAT,
  computed_at      TIMESTAMPTZ NOT NULL DEFAULT now(),
  PRIMARY KEY (grid_point_id, category, subcategory, travel_mode)
);

CREATE INDEX IF NOT EXISTS idx_grid_poi_details_lookup
  ON grid_poi_details (grid_point_id, travel_mode);

-- ─── Isochrone cache ──────────────────────────────────────────────────────────

CREATE TABLE IF NOT EXISTS isochrone_cache (
  id           BIGSERIAL PRIMARY KEY,
  origin_geom  geometry(Point, 4326) NOT NULL,
  travel_mode  TEXT NOT NULL,
  contours_min INTEGER[] NOT NULL,
  result       JSONB NOT NULL,
  created_at   TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX IF NOT EXISTS idx_isochrone_origin
  ON isochrone_cache USING GIST (origin_geom);
CREATE INDEX IF NOT EXISTS idx_isochrone_created
  ON isochrone_cache (created_at);

-- Auto-expire isochrone cache entries older than 30 days
-- (handled by periodic cleanup or TTL logic in app)