"""The per-company running score ledger under /data/ledger.

Layout:
    /data/ledger/<slug>/company.json       identity, aliases, pinned targets,
                                           extracted forward targets, history
    /data/ledger/<slug>/decks/<id>.json    full scoring record per graded deck

Config (bm_config `companies`) is the source of truth for name/aliases/pinned
targets; extracted_targets and history are owned by the grading pipeline.
Re-graded decks supersede (rename, never delete) the previous record.
"""
from __future__ import annotations

import json
import os
from datetime import datetime, timezone

import decks as decks_mod


def atomic_write_json(path: str, obj) -> None:
    """Write JSON via temp file + os.replace so readers never see a torn file."""
    tmp = f"{path}.tmp"
    with open(tmp, "w", encoding="utf-8") as f:
        json.dump(obj, f, indent=2, sort_keys=False)
        f.write("\n")
    os.replace(tmp, path)


def parse_alias_lines(text: str) -> dict:
    """Parse newline-separated "canonical=alias1;alias2" lines into a dict."""
    out: dict[str, list[str]] = {}
    for line in (text or "").splitlines():
        line = line.strip()
        if not line or "=" not in line:
            continue
        canonical, _, rest = line.partition("=")
        canonical = canonical.strip().lower()
        aliases = [a.strip() for a in rest.split(";") if a.strip()]
        if canonical and aliases:
            out[canonical] = aliases
    return out


class Ledger:
    def __init__(self, base_dir: str):
        self.base = base_dir
        os.makedirs(self.base, exist_ok=True)

    # ------------------------------------------------------------- paths
    def _company_dir(self, slug: str) -> str:
        return os.path.join(self.base, slug)

    def _company_path(self, slug: str) -> str:
        return os.path.join(self._company_dir(slug), "company.json")

    def _decks_dir(self, slug: str) -> str:
        return os.path.join(self._company_dir(slug), "decks")

    # ------------------------------------------------------------- companies
    def ensure_company(self, slug: str, name: str | None = None) -> dict:
        """Load the company, creating a skeleton entry on first sight."""
        existing = self.get_company(slug)
        if existing is not None:
            return existing
        company = {
            "schema_version": 1,
            "slug": slug,
            "name": name or slug,
            "auto_created": name is None,
            "kpi_aliases": {},
            "pinned_targets": [],
            "extracted_targets": {},
            "history": [],
        }
        os.makedirs(self._company_dir(slug), exist_ok=True)
        atomic_write_json(self._company_path(slug), company)
        return company

    def get_company(self, slug: str) -> dict | None:
        try:
            with open(self._company_path(slug), encoding="utf-8") as f:
                return json.load(f)
        except (FileNotFoundError, json.JSONDecodeError):
            return None

    def all_slugs(self) -> list[str]:
        if not os.path.isdir(self.base):
            return []
        return sorted(d for d in os.listdir(self.base)
                      if os.path.isfile(self._company_path(d)))

    def all_companies(self) -> list[dict]:
        return [c for c in (self.get_company(s) for s in self.all_slugs()) if c]

    def merge_config_companies(self, companies_cfg: list) -> None:
        """Config wins for name/aliases/pinned targets; ledger keeps the rest."""
        for cc in companies_cfg or []:
            name = (cc.get("name") or "").strip()
            slug = (cc.get("slug") or "").strip() or decks_mod.slugify(name)
            company = self.ensure_company(slug, name or slug)
            company["name"] = name or company["name"]
            company["auto_created"] = False
            company["kpi_aliases"] = parse_alias_lines(cc.get("kpiAliases") or "")
            company["pinned_targets"] = list(cc.get("pinnedTargets") or [])
            atomic_write_json(self._company_path(slug), company)

    # ------------------------------------------------------------- targets
    def prior_targets(self, slug: str, period: str) -> list[dict]:
        """Forward targets an earlier deck set for `period` (this deck's exam)."""
        company = self.get_company(slug)
        if not company or not period:
            return []
        return (company.get("extracted_targets", {}).get(period) or {}).get("targets", [])

    # ------------------------------------------------------------- decks
    def record_deck(self, slug: str, record: dict, forward_targets: list[dict]) -> str:
        """Persist a scoring record + its forward targets. Returns the deck path.

        A re-graded deck_id supersedes (renames) the old record; the history
        entry for the same period is replaced; a target period's forward
        targets are replaced wholesale when set by a newer (or same) deck."""
        company = self.ensure_company(slug)
        deck_id = record["deck_id"]
        ddir = self._decks_dir(slug)
        os.makedirs(ddir, exist_ok=True)
        deck_path = os.path.join(ddir, f"{deck_id}.json")
        if os.path.exists(deck_path):
            stamp = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
            os.replace(deck_path, os.path.join(ddir, f"{deck_id}.superseded-{stamp}.json"))
        atomic_write_json(deck_path, record)

        period = record.get("period")
        entry = {"period": period, "composite": record.get("composite"),
                 "graded_at": record.get("graded_at"),
                 "deck_file": f"decks/{deck_id}.json"}
        history = [h for h in company.get("history", []) if h.get("period") != period]
        history.append(entry)
        history.sort(key=lambda h: decks_mod.period_sort_key(h.get("period")))
        company["history"] = history

        extracted = company.setdefault("extracted_targets", {})
        from_key = decks_mod.period_sort_key(period)
        by_period: dict[str, list[dict]] = {}
        for ft in forward_targets or []:
            tp = ft.get("target_period")
            if tp:
                by_period.setdefault(tp, []).append(ft)
        for tp, targets in by_period.items():
            cur = extracted.get(tp)
            if cur is None or from_key >= decks_mod.period_sort_key(cur.get("from_deck")):
                extracted[tp] = {"from_deck": period, "targets": targets}

        atomic_write_json(self._company_path(slug), company)
        return deck_path

    def deck_record(self, slug: str, deck_id: str) -> dict | None:
        try:
            with open(os.path.join(self._decks_dir(slug), f"{deck_id}.json"),
                      encoding="utf-8") as f:
                return json.load(f)
        except (FileNotFoundError, json.JSONDecodeError):
            return None

    def deck_records(self, slug: str) -> list[dict]:
        """All live (non-superseded) deck records, oldest period first."""
        ddir = self._decks_dir(slug)
        if not os.path.isdir(ddir):
            return []
        out: list[dict] = []
        for fn in sorted(os.listdir(ddir)):
            if not fn.endswith(".json") or ".superseded-" in fn:
                continue
            try:
                with open(os.path.join(ddir, fn), encoding="utf-8") as f:
                    out.append(json.load(f))
            except (json.JSONDecodeError, OSError):
                continue
        out.sort(key=lambda r: decks_mod.period_sort_key(r.get("period")))
        return out