#!/usr/bin/env python3
"""kb-lint-fm.py —— frontmatter 校验器

单一真相源：读 meta/kb-contract.yaml 判定 type 白名单 / 必填矩阵 / enum，
绝不硬编码 type 或字段清单。

用法:
    python3 tools/kb-lint-fm.py [路径...]        # 默认扫全库
    python3 tools/kb-lint-fm.py projects/foo     # 只扫某目录/文件

退出码:
    0 = 全部通过
    1 = 有错误（缺硬必填 / 未激活 type / enum 非法 / 派生必填缺失）
    2 = 运行环境问题（缺 PyYAML / 缺契约文件）
供 CC 判定：非 0 即需处理。
"""
import sys
import os
import re
import fnmatch

try:
    import yaml
except ImportError:
    print("ERROR: 需要 PyYAML。请运行: pip install pyyaml", file=sys.stderr)
    sys.exit(2)

ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
CONTRACT_PATH = os.path.join(ROOT, "meta", "kb-contract.yaml")

FM_RE = re.compile(r"^---\s*\n(.*?)\n---\s*\n", re.DOTALL)


def load_contract():
    if not os.path.isfile(CONTRACT_PATH):
        print(f"ERROR: 缺契约文件 {CONTRACT_PATH}", file=sys.stderr)
        sys.exit(2)
    with open(CONTRACT_PATH, encoding="utf-8") as f:
        return yaml.safe_load(f)


def is_exempt(rel, patterns):
    for pat in patterns:
        if fnmatch.fnmatch(rel, pat) or fnmatch.fnmatch(rel, pat.rstrip("/") + "/*"):
            return True
    # 目录型 glob（docs/**）也匹配 docs/ 下任意层
    for pat in patterns:
        if pat.endswith("/**") and rel.startswith(pat[:-2]):
            return True
    return False


def parse_frontmatter(text):
    m = FM_RE.match(text)
    if not m:
        return None, "缺 frontmatter 块（--- 开头）"
    try:
        data = yaml.safe_load(m.group(1))
    except yaml.YAMLError as e:
        return None, f"frontmatter YAML 解析失败: {e}"
    if not isinstance(data, dict):
        return None, "frontmatter 不是键值映射"
    return data, None


def collect_md(paths):
    files = []
    for p in paths:
        ap = os.path.abspath(p)
        if os.path.isfile(ap) and ap.endswith(".md"):
            files.append(ap)
        elif os.path.isdir(ap):
            for dp, _, fns in os.walk(ap):
                for fn in fns:
                    if fn.endswith(".md"):
                        files.append(os.path.join(dp, fn))
    return sorted(set(files))


def check_derived(data, rules):
    """返回派生必填字段名列表"""
    req = []
    t = data.get("type")
    src = data.get("source")
    for rule in rules or []:
        w = rule.get("when", {})
        ok = True
        if "type_in" in w and t not in w["type_in"]:
            ok = False
        if "source_in" in w and src not in w["source_in"]:
            ok = False
        if ok:
            req.extend(rule.get("require", []))
    return req


def main():
    contract = load_contract()
    types = {t["name"]: t for t in contract.get("types", [])}
    active = {n for n, t in types.items() if t.get("active")}
    fields = contract.get("fields", {})
    enums = contract.get("enums", {})
    exempt = contract.get("frontmatter_exempt", [])
    source_exempt_types = set(contract.get("source_exempt_types", []))
    derived = contract.get("derived_rules", [])

    always_required = [f for f, spec in fields.items()
                       if spec.get("required") == "always"]

    targets = sys.argv[1:] or [ROOT]
    files = collect_md(targets)

    errors = 0
    warnings = 0
    checked = 0

    for fp in files:
        rel = os.path.relpath(fp, ROOT)
        if is_exempt(rel, exempt):
            continue
        checked += 1
        with open(fp, encoding="utf-8") as f:
            text = f.read()

        data, err = parse_frontmatter(text)
        if err:
            print(f"[ERROR] {rel}: {err}")
            errors += 1
            continue

        # type 硬必填 + 白名单
        t = data.get("type")
        if not t:
            print(f"[ERROR] {rel}: 缺硬必填字段 type")
            errors += 1
            continue
        if t not in types:
            print(f"[ERROR] {rel}: 未知 type '{t}'（不在契约中，扩展需改 kb-contract.yaml）")
            errors += 1
        elif t not in active:
            print(f"[ERROR] {rel}: type '{t}' 已登记但未激活（改契约 active: true 再用）")
            errors += 1

        # 其余硬必填
        for f_ in always_required:
            if f_ == "type":
                continue
            if data.get(f_) in (None, ""):
                print(f"[ERROR] {rel}: 缺硬必填字段 {f_}")
                errors += 1

        # 派生必填（project 型豁免溯源）
        req = check_derived(data, derived)
        if t in source_exempt_types:
            req = [r for r in req if r not in ("source", "source_link")]
        for f_ in req:
            if data.get(f_) in (None, ""):
                print(f"[ERROR] {rel}: 派生必填缺失 {f_}（type={t} + source 条件触发）")
                errors += 1

        # enum 校验
        for f_, allowed in enums.items():
            v = data.get(f_)
            if v is not None and v not in allowed:
                print(f"[ERROR] {rel}: 字段 {f_}='{v}' 不在 enum {allowed}")
                errors += 1

        # 软提示：建议但非必填的 title
        if not data.get("title"):
            print(f"[WARN]  {rel}: 建议补 title（AI 可自动=H1 或文件名）")
            warnings += 1

    print(f"\n检查 {checked} 页 | 错误 {errors} | 警告 {warnings}")
    sys.exit(1 if errors else 0)


if __name__ == "__main__":
    main()