#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Host data adapter for Webcrumbs shared-ui plugins.

This module is intentionally read-only. It converts the canonical
MOMO/PChome competitor intelligence payload into the small
``window.StockPlatformSharedUI`` shape consumed by the shared plugin
runtime.
"""

from __future__ import annotations

from typing import Any

from services.competitor_intel_repository import (
    fetch_competitor_coverage,
    fetch_top_competitor_risks,
)


def _num(value: Any, default: float = 0.0) -> float:
    try:
        return float(value)
    except (TypeError, ValueError):
        return default


def _money(value: Any) -> str:
    return f"NT${_num(value):,.0f}"


def _short_text(value: Any, limit: int = 42) -> str:
    text = str(value or "").strip()
    if len(text) <= limit:
        return text
    return f"{text[:limit - 1]}…"


def _risk_level(gap_pct: float) -> str:
    if gap_pct >= 15:
        return "high"
    if gap_pct >= 8:
        return "medium"
    return "watch"


def _is_direct_price_alert(item: dict) -> bool:
    return (
        str(item.get("match_type") or "") == "exact"
        and str(item.get("price_basis") or "") == "total_price"
        and str(item.get("alert_tier") or "") == "price_alert_exact"
    )


def _empty_payload(reason: str = "no_price_alert_exact") -> dict:
    return {
        "marketSnapshot": [
            {
                "name": "MOMO/PChome exact price alert",
                "price": "not_available",
                "change_pct": "not_available",
                "freshness_status": reason,
            }
        ],
        "aiCandidate": {
            "ticker": "-",
            "name": "目前沒有可直接告警的 exact 同款價差",
            "thesis": "資料源已接入，但目前沒有符合 exact / total_price / price_alert_exact 的高風險候選；非同款、單位價或變體候選仍須留在人工覆核隊列。",
            "confidence_score": "not_available",
            "risk_level": "none",
            "release_status": "blocked",
            "evidence_refs": ["competitor_prices", "price_records", reason],
            "updated_at": "read_only",
        },
    }


def _coverage_metadata(coverage: dict, row_count: int) -> dict:
    return {
        "source": "competitor_intel_repository",
        "matched_count": int(coverage.get("valid_matches") or coverage.get("matched_count") or 0),
        "coverage_rate": _num(coverage.get("match_rate")),
        "fresh_match_count": int(coverage.get("fresh_matches") or coverage.get("fresh_match_count") or 0),
        "fresh_match_rate": _num(coverage.get("fresh_match_rate")),
        "stale_match_count": int(coverage.get("stale_matches") or coverage.get("stale_match_count") or 0),
        "pending_match_count": int(coverage.get("pending") or coverage.get("pending_match_count") or 0),
        "row_count": row_count,
        "writes_database": False,
        "calls_llm": False,
        "fetches_external": False,
    }


def build_webcrumbs_marketplace_host_data(engine=None, limit: int = 5) -> dict:
    """Build read-only host data for the Webcrumbs diagnostic page.

    Args:
        engine: Optional SQLAlchemy engine. When omitted, the default
            momo-pro database manager is used.
        limit: Maximum number of price-alert rows exposed to the shared-ui
            preview. Kept small because this powers a diagnostic surface.
    """
    if engine is None:
        from database.manager import DatabaseManager

        engine = DatabaseManager().engine

    limit = max(1, min(int(limit or 5), 8))
    raw_risks = fetch_top_competitor_risks(engine, limit=max(limit * 4, 20)) or []
    risks = [item for item in raw_risks if _is_direct_price_alert(item)][:limit]
    coverage = fetch_competitor_coverage(engine) or {}

    if not risks:
        payload = _empty_payload("no_current_exact_risk")
        payload["metadata"] = _coverage_metadata(coverage, row_count=0)
        return payload

    rows = []
    for item in risks[:limit]:
        gap_pct = _num(item.get("gap_pct"))
        momo_price = _num(item.get("momo_price"))
        pchome_price = _num(item.get("pchome_price"))
        rows.append({
            "name": f"{item.get('sku') or '-'} {_short_text(item.get('name'))}",
            "price": pchome_price,
            "change_pct": gap_pct,
            "freshness_status": item.get("alert_tier") or "price_alert_exact",
            "momo_price": momo_price,
            "pchome_price": pchome_price,
            "match_score": _num(item.get("match_score")),
            "competitor_product_id": item.get("pchome_id") or "",
            "competitor_product_name": _short_text(item.get("pchome_name"), 48),
        })

    top = risks[0]
    top_gap = _num(top.get("gap_pct"))
    top_score = _num(top.get("match_score"))
    sku = str(top.get("sku") or "-")
    evidence_refs = ["competitor_prices", "price_records", "exact", "total_price", "price_alert_exact"]

    return {
        "marketSnapshot": rows,
        "aiCandidate": {
            "ticker": sku,
            "name": _short_text(top.get("name"), 58),
            "thesis": (
                f"MOMO {_money(top.get('momo_price'))} vs PChome {_money(top.get('pchome_price'))}，"
                f"價差 {top_gap:+.1f}%（MOMO - PChome）。"
                f"此候選已通過 exact / total_price / price_alert_exact 只讀過濾，"
                f"match_score={top_score:.2f}；仍需人工確認促銷、庫存與商品頁條件後再採取價格或曝光調整。"
            ),
            "confidence_score": round(top_score, 2),
            "risk_level": _risk_level(top_gap),
            "release_status": "review_required",
            "evidence_refs": evidence_refs,
            "updated_at": top.get("crawled_at") or "latest_competitor_prices",
        },
        "metadata": _coverage_metadata(coverage, row_count=len(rows)),
    }