-- ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-- Migration 04 — Bug Fix: distance unit correction + column rename
-- ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-- BUG-02: tracksolid.trips.distance_m was storing millimetres not metres.
--
-- Root cause: ingestion code applied `km * 1000` but the API already returns
-- values in km, producing mm. Confirmed by cross-checking stored values against
-- avg_speed_kmh × driving_time_s — e.g. 4,203,000 stored for a 4.203 km trip.
--
-- Fix applied here:
--   1. Divide all existing rows by 1,000,000 to convert mm → km.
--   2. Rename the column to distance_km to eliminate future ambiguity.
--
-- Corresponding code fix: removed * 1000 from poll_trips() in
-- ingest_movement_rev.py and push_trip_report() in webhook_receiver_rev.py.
-- Both now store the raw API value directly as km.
--
-- Run once against tracksolid_db before deploying updated ingestion containers.
-- ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

BEGIN;

-- Step 1: Correct all existing stored values (mm → km)
UPDATE tracksolid.trips
SET distance_m = distance_m / 1000000.0
WHERE distance_m IS NOT NULL;

-- Step 2: Rename column
ALTER TABLE tracksolid.trips
  RENAME COLUMN distance_m TO distance_km;

-- Step 3: Update column comment
COMMENT ON COLUMN tracksolid.trips.distance_km
  IS 'Trip distance in kilometres. Corrected from mm storage on migration 04 (2026-04-10).';

COMMIT;
