-- CSG 长期归档 v5 (2026-09-22, VPS-78)
--
-- 背景：v3 修好了 job（1008 → 1010）并回填，但 csg_daily_snapshot() 写 day 行时用的是
--   「昨日用电 × 当前档费率」**单一费率**且未舍入，而 v3 的回填（07-01..09-19）用的是
--   「当月累积的边际差分」并 round(...,2)。两套口径混在同一列：
--     · 实测今天只差**精度**（3 行：2026-08-28 / 09-19 / 09-20，总差 -0.01 元）；
--     · 但一旦某个**跨档日**由夜间任务写出，就会与历史口径不一致，并破坏
--       「day 费用之和 ≈ 阶梯月费用」这条 v3 建立的验收不变量。
--     · 时限：2026-09-22 时 csg_current_ladder_remaining_kwh = 80.6、本月日均 8.97
--       → 约 2026-09-29 跨入二档。
--
-- 本文件的四个动作（幂等，可重复执行）：
--   1. csg_ladder_cost_raw(kwh, month) —— **无舍入**的阶梯费用助手。
--      v3 回填的算法是 round(精确c1 − 精确c0, 2)。若直接用
--      csg_ladder_cost(c1) − csg_ladder_cost(c0)，会**二次舍入**（7 月实测 1 天差 0.01），
--      故新增 raw 版，只在最后舍入一次。
--   2. csg_daily_snapshot() v5 —— day cost 改为「当月累积边际差分 + round(...,2)」；
--      并把 p_month 的计算**上移到计费之前**，加**跨月守卫**
--      （每月 1 日的 d 落在上月，此时 m_usage 是「新月份」累计，不能作起点，否则为负）。
--      同时把「数据日期」与「当日用量」改为取**同一个实体同一行**
--      （sensor.0800041935246530_latest_day_kwh）：v3 用 latest_day_kwh 取日期、
--      却用 yesterday_kwh 取数值，两个实体可能错配；且 latest_day_kwh 的归档更完整
--      （含 2026-09-06 = 9.29 这条 yesterday_kwh 没有的观测）。
--   3. 一次性归一：把历史 day 行的 cost 按新口径重算（实测仅 3 行变化，总差 -0.01）。
--   4. csg_backfill_missing_days() + job 1011 —— **断档自愈**：只 INSERT 缺失日期，
--      ON CONFLICT DO NOTHING，**绝不覆盖既有行**；数据源是 scribe.states_raw 里
--      latest_day_kwh 的 (latest_day_date 属性, value) 观测对（该属性 v3 起就有归档）。
--
-- 回滚（脚本已自动建快照表 csg_history_bak_20260922）：
--   BEGIN;
--     SELECT delete_job((SELECT job_id FROM timescaledb_information.jobs
--                         WHERE proc_name='csg_backfill_missing_days'));
--     DROP FUNCTION IF EXISTS public.csg_backfill_missing_days(integer, jsonb);
--     DROP FUNCTION IF EXISTS public.csg_ladder_cost_raw(numeric, date);
--     -- v3 的 csg_daily_snapshot 用 compose/pgdb/csg-snapshot-v3.sql 的原文重建即可
--     DELETE FROM csg_history; INSERT INTO csg_history SELECT * FROM csg_history_bak_20260922;
--   COMMIT;
--   （或整体放弃归档：DROP TABLE csg_history + 删 job，见 hosts/pgdb.md 回滚段）

\set ON_ERROR_STOP on

BEGIN;

-- ---------- 0. 回滚快照（只建一次） ----------
CREATE TABLE IF NOT EXISTS public.csg_history_bak_20260922 AS TABLE public.csg_history;

-- ---------- 1. 无舍入阶梯费用助手（差分用） ----------
CREATE OR REPLACE FUNCTION public.csg_ladder_cost_raw(kwh numeric, month_date date)
 RETURNS numeric
 LANGUAGE sql
 IMMUTABLE
AS $function$
  SELECT CASE
    WHEN kwh IS NULL OR kwh <= 0 THEN 0::numeric
    WHEN kwh <= (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 260 ELSE 200 END)
      THEN kwh * 0.589
    WHEN kwh <= (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 600 ELSE 400 END)
      THEN (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 260 ELSE 200 END) * 0.589
         + (kwh - (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 260 ELSE 200 END)) * 0.639
    ELSE (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 260 ELSE 200 END) * 0.589
       + ((CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 600 ELSE 400 END)
          - (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 260 ELSE 200 END)) * 0.639
       + (kwh - (CASE WHEN extract(month FROM month_date) BETWEEN 5 AND 10 THEN 600 ELSE 400 END)) * 0.889
  END;
$function$;

-- ---------- 2. csg_daily_snapshot() v5 ----------
CREATE OR REPLACE FUNCTION public.csg_daily_snapshot(
    job_id integer DEFAULT NULL,
    config jsonb DEFAULT NULL
)
RETURNS void
LANGUAGE plpgsql
AS $function$
DECLARE
  d date;
  v_usage numeric; v_cost numeric; v_ladder text; v_balance numeric;
  m_usage numeric;
  p_month date; p_usage numeric; prev_usage numeric; c0 numeric; c1 numeric;
BEGIN
  -- 数据日期与当日用量取【同一实体的同一行】：latest_day_kwh
  -- （v3 的 d 来自它的 latest_day_date，但 v_usage 来自另一个实体 yesterday_kwh）
  SELECT (s.attributes->>'latest_day_date')::date, s.value
    INTO d, v_usage
    FROM states_raw s JOIN entities e ON e.id = s.metadata_id
   WHERE e.entity_id = 'sensor.0800041935246530_latest_day_kwh'
     AND s.value IS NOT NULL
     AND s.attributes->>'latest_day_date' IS NOT NULL
   ORDER BY s.time DESC LIMIT 1;
  d := COALESCE(d, CURRENT_DATE - 1);

  -- 一律取「最新有值行」：轮询先写瞬态 unknown、~4s 后才写有值行
  SELECT s.value INTO v_cost   FROM states_raw s JOIN entities e ON e.id=s.metadata_id
    WHERE e.entity_id='sensor.0800041935246530_latest_day_cost' AND s.value IS NOT NULL ORDER BY s.time DESC LIMIT 1;
  SELECT s.state INTO v_ladder FROM states_raw s JOIN entities e ON e.id=s.metadata_id
    WHERE e.entity_id='sensor.csg_current_ladder' AND s.state IS NOT NULL AND s.state NOT IN ('unknown','unavailable') ORDER BY s.time DESC LIMIT 1;
  SELECT s.value INTO v_balance FROM states_raw s JOIN entities e ON e.id=s.metadata_id
    WHERE e.entity_id='sensor.0800041935246530_balance' AND s.value IS NOT NULL ORDER BY s.time DESC LIMIT 1;
  SELECT s.value INTO m_usage  FROM states_raw s JOIN entities e ON e.id=s.metadata_id
    WHERE e.entity_id='sensor.0800041935246530_this_month_total_usage' AND s.value IS NOT NULL ORDER BY s.time DESC LIMIT 1;

  -- 月归属必须在计费之前算：跨月守卫要用它
  p_month := date_trunc('month', d)::date;

  -- 日费用：与 v3 回填同口径 = 当月累积的边际差分，只在最后舍入一次。
  -- 原生 latest_day_cost 从未有值（集成侧恒 unknown），故这里是唯一路径。
  IF v_cost IS NULL AND v_usage IS NOT NULL THEN
    IF p_month = date_trunc('month', CURRENT_DATE)::date THEN
      -- 当月日：起点 = 本月累计 − 当日用量
      IF m_usage IS NOT NULL THEN
        c1 := m_usage;
        c0 := m_usage - v_usage;
      END IF;
    ELSE
      -- 上月日（每月 1 日必现，因数据滞后一天）：起点 = 该月已归档 day 行之和
      SELECT COALESCE(sum(h.usage_kwh), 0) INTO c0
        FROM csg_history h
       WHERE h.kind='day' AND h.period >= p_month AND h.period < d;
      c1 := c0 + v_usage;
    END IF;
    IF c0 IS NOT NULL AND c1 IS NOT NULL AND c0 >= 0 THEN
      v_cost := round(public.csg_ladder_cost_raw(c1, p_month)
                    - public.csg_ladder_cost_raw(c0, p_month), 2);
    END IF;
  END IF;

  INSERT INTO csg_history (period, kind, usage_kwh, cost, ladder, balance)
  VALUES (d, 'day', v_usage, v_cost, v_ladder, v_balance)
  ON CONFLICT (period, kind) DO UPDATE SET
    usage_kwh  = COALESCE(EXCLUDED.usage_kwh,  csg_history.usage_kwh),
    cost       = COALESCE(EXCLUDED.cost,       csg_history.cost),
    ladder     = COALESCE(EXCLUDED.ladder,     csg_history.ladder),
    balance    = COALESCE(EXCLUDED.balance,    csg_history.balance),
    updated_at = now();

  -- month 行按 d 所属月份归属（v3：修掉翻月时用错月份累计的 bug）
  IF p_month = date_trunc('month', CURRENT_DATE)::date THEN
    -- 当月：集成本月累计优先，缺失则退回 day 行汇总；费用一律阶梯重算
    SELECT COALESCE(m_usage, sum(h.usage_kwh)) INTO p_usage
      FROM csg_history h
     WHERE h.kind='day' AND h.period >= p_month AND h.period < (p_month + interval '1 month');
  ELSE
    -- 上月/更早：只信该月 day 行（集成翻月时 last_month_* 有瞬态误值）
    SELECT sum(h.usage_kwh) INTO p_usage
      FROM csg_history h
     WHERE h.kind='day' AND h.period >= p_month AND h.period < (p_month + interval '1 month');
    SELECT h.usage_kwh INTO prev_usage FROM csg_history h
     WHERE h.kind='month' AND h.period = p_month;
    IF p_usage IS NULL OR (prev_usage IS NOT NULL AND prev_usage > p_usage) THEN
      RETURN;  -- day 行不完整，保留已有 month 行，不降级
    END IF;
  END IF;

  IF p_usage IS NOT NULL AND p_usage > 0 THEN
    INSERT INTO csg_history (period, kind, usage_kwh, cost)
    VALUES (p_month, 'month', p_usage, public.csg_ladder_cost(p_usage, p_month))
    ON CONFLICT (period, kind) DO UPDATE SET
      usage_kwh  = EXCLUDED.usage_kwh,
      cost       = EXCLUDED.cost,
      updated_at = now();
  END IF;
END $function$;

-- ---------- 3. 一次性归一：历史 day 行 cost 按新口径重算 ----------
-- 幂等：只更新与新口径不同的行。实测（写入前 dry-run）仅 3 行变化、总差 -0.01。
WITH cum AS (
  SELECT period, usage_kwh, cost,
         sum(usage_kwh) OVER (PARTITION BY date_trunc('month', period)
                              ORDER BY period ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS c1
    FROM csg_history
   WHERE kind='day' AND usage_kwh IS NOT NULL
), priced AS (
  SELECT period,
         round(public.csg_ladder_cost_raw(c1, period)
             - public.csg_ladder_cost_raw(c1 - usage_kwh, period), 2) AS new_cost
    FROM cum
)
UPDATE csg_history h
   SET cost = p.new_cost, updated_at = now()
  FROM priced p
 WHERE h.kind='day' AND h.period = p.period
   AND h.cost IS DISTINCT FROM p.new_cost;

-- ---------- 4. 断档自愈（只补缺失，不覆盖既有） ----------
CREATE OR REPLACE FUNCTION public.csg_backfill_missing_days(
    job_id integer DEFAULT NULL,
    config jsonb DEFAULT NULL
)
RETURNS void
LANGUAGE plpgsql
AS $function$
DECLARE
  lookback int := COALESCE((config->>'lookback_days')::int, 45);
  dd date;
  v_usage numeric;
  c0 numeric; c1 numeric;
  v_ladder text;
  mm date;
BEGIN
  -- 4a. 补缺失的 day 行（只 INSERT，绝不覆盖）
  FOR dd IN
    SELECT g::date
      FROM generate_series(CURRENT_DATE - lookback, CURRENT_DATE - 1, INTERVAL '1 day') g
     WHERE NOT EXISTS (SELECT 1 FROM csg_history h WHERE h.kind='day' AND h.period = g::date)
     ORDER BY 1
  LOOP
    -- 该数据日的观测：同一实体同时给出日期与数值
    SELECT s.value INTO v_usage
      FROM states_raw s JOIN entities e ON e.id = s.metadata_id
     WHERE e.entity_id = 'sensor.0800041935246530_latest_day_kwh'
       AND s.value IS NOT NULL
       AND s.attributes->>'latest_day_date' = dd::text
     ORDER BY s.time DESC LIMIT 1;
    CONTINUE WHEN v_usage IS NULL;   -- 上游没有这天的数据，不写空行

    SELECT COALESCE(sum(h.usage_kwh), 0) INTO c0
      FROM csg_history h
     WHERE h.kind='day'
       AND h.period >= date_trunc('month', dd)::date
       AND h.period < dd;
    c1 := c0 + v_usage;
    v_ladder := CASE
      WHEN c1 <= (CASE WHEN extract(month FROM dd) BETWEEN 5 AND 10 THEN 260 ELSE 200 END) THEN '一档'
      WHEN c1 <= (CASE WHEN extract(month FROM dd) BETWEEN 5 AND 10 THEN 600 ELSE 400 END) THEN '二档'
      ELSE '三档' END;

    INSERT INTO csg_history (period, kind, usage_kwh, cost, ladder)
    VALUES (dd, 'day', v_usage,
            round(public.csg_ladder_cost_raw(c1, dd) - public.csg_ladder_cost_raw(c0, dd), 2),
            v_ladder)
    ON CONFLICT (period, kind) DO NOTHING;
  END LOOP;

  -- 4b. 受影响月份的 month 行重算（只升不降，与主函数同语义）
  FOR mm IN
    SELECT DISTINCT date_trunc('month', h.period)::date
      FROM csg_history h
     WHERE h.kind='day' AND h.period >= CURRENT_DATE - lookback
     ORDER BY 1
  LOOP
    SELECT sum(h.usage_kwh) INTO c1
      FROM csg_history h
     WHERE h.kind='day' AND h.period >= mm AND h.period < (mm + interval '1 month');
    SELECT h.usage_kwh INTO c0 FROM csg_history h WHERE h.kind='month' AND h.period = mm;
    IF c1 IS NOT NULL AND c1 > 0 AND (c0 IS NULL OR c1 > c0) THEN
      INSERT INTO csg_history (period, kind, usage_kwh, cost)
      VALUES (mm, 'month', c1, public.csg_ladder_cost(c1, mm))
      ON CONFLICT (period, kind) DO UPDATE SET
        usage_kwh  = EXCLUDED.usage_kwh,
        cost       = EXCLUDED.cost,
        updated_at = now();
    END IF;
  END LOOP;
END $function$;

-- 重挂自愈任务：每天 15:10 UTC = 23:10 Asia/Shanghai（排在 14:30 UTC 的主任务之后）
DO $do$
BEGIN
  IF NOT EXISTS (SELECT 1 FROM timescaledb_information.jobs WHERE proc_name = 'csg_backfill_missing_days') THEN
    PERFORM add_job(proc              => 'public.csg_backfill_missing_days'::regproc,
                    schedule_interval => INTERVAL '1 day',
                    initial_start     => date_trunc('day', now() AT TIME ZONE 'UTC')
                                         + INTERVAL '1 day 15 hours 10 minutes',
                    timezone          => 'UTC');
  END IF;
END
$do$;

COMMIT;