"""SQL 語法風險審查器。

此工具只審查孤立 SQL corpus 裡的危險語法與測試 payload。
它不宣稱已驗證應用程式漏洞，因為缺少 application source/sink context。
"""

from __future__ import annotations

import re
from dataclasses import dataclass
from typing import Any


@dataclass(frozen=True)
class SqlPatternSpec:
    """SQL review pattern 的固定規格。"""

    syntax_pattern: str
    category: str
    regex: re.Pattern[str]
    risk_note: str


SQL_REVIEW_PATTERNS: tuple[SqlPatternSpec, ...] = (
    SqlPatternSpec(
        syntax_pattern="boolean_blind",
        category="sql_injection_payload",
        regex=re.compile(r"(?i)(?:\bOR\b|\bAND\b)\s+(?:1\s*=\s*1|'1'\s*=\s*'1')"),
        risk_note="Boolean-based SQL injection payload. Requires application input-flow context.",
    ),
    SqlPatternSpec(
        syntax_pattern="union_select",
        category="sql_injection_payload",
        regex=re.compile(r"(?i)\bUNION\s+(?:ALL\s+)?SELECT\b"),
        risk_note="UNION-based SQL injection payload. Requires application input-flow context.",
    ),
    SqlPatternSpec(
        syntax_pattern="time_based",
        category="sql_injection_payload",
        regex=re.compile(r"(?i)\b(?:SLEEP\s*\(|BENCHMARK\s*\(|WAITFOR\s+DELAY|pg_sleep\s*\()"),
        risk_note="Time-based SQL injection payload. Requires runtime and database context.",
    ),
    SqlPatternSpec(
        syntax_pattern="error_based",
        category="sql_injection_payload",
        regex=re.compile(r"(?i)\b(?:EXTRACTVALUE\s*\(|UPDATEXML\s*\(|CONVERT\s*\(|CAST\s*\()"),
        risk_note="Error-based SQL injection payload. Requires database error exposure context.",
    ),
    SqlPatternSpec(
        syntax_pattern="stacked_query",
        category="dangerous_sql_syntax",
        regex=re.compile(r"(?i);\s*(?:DROP|EXEC|CREATE\s+USER|GRANT\s+ALL|ALTER|TRUNCATE|DELETE)\b"),
        risk_note="Stacked query or destructive statement pattern. Requires execution context.",
    ),
    SqlPatternSpec(
        syntax_pattern="dynamic_sql",
        category="dangerous_sql_syntax",
        regex=re.compile(r"(?i)(?:\bEXEC\s*\(@?\w+\)|\bsp_executesql\b|\bEXECUTE\s+IMMEDIATE\b|\bPREPARE\s+\w+\s+FROM\b)"),
        risk_note="Dynamic SQL execution pattern. Requires parameterization and source context.",
    ),
    SqlPatternSpec(
        syntax_pattern="nosql_payload",
        category="nosql_injection_payload",
        regex=re.compile(r"(?i)(?:['\"]?\$(?:gt|gte|lt|lte|ne|in|nin|regex|where)['\"]?\s*:|\$where\b)"),
        risk_note="NoSQL-style injection payload. Requires datastore and request parsing context.",
    ),
)


def _line_no(text: str, offset: int) -> int:
    """依字元 offset 計算 1-based 行號。"""
    return text[:offset].count("\n") + 1


def _snippet(value: str, limit: int = 160) -> str:
    """回傳短 snippet，避免 review output 過長。"""
    compact = " ".join(value.strip().split())
    return compact[:limit]


def review_sql_syntax(sql_text: str) -> dict[str, Any]:
    """
    審查 SQL corpus 中的危險語法與 injection payload。

    Returns:
        `sql_syntax_review` 契約；所有 finding 都標示
        `requires_application_context=true`，避免被下游包裝成 verified CWE。
    """
    if not isinstance(sql_text, str):
        sql_text = str(sql_text)

    findings: list[dict[str, Any]] = []
    seen: set[tuple[str, int, str]] = set()

    for spec in SQL_REVIEW_PATTERNS:
        for match in spec.regex.finditer(sql_text):
            line_no = _line_no(sql_text, match.start())
            snippet = _snippet(match.group(0))
            key = (spec.syntax_pattern, line_no, snippet)
            if key in seen:
                continue
            seen.add(key)
            findings.append({
                "syntax_pattern": spec.syntax_pattern,
                "line_no": line_no,
                "category": spec.category,
                "snippet": snippet,
                "risk_note": spec.risk_note,
                "requires_application_context": True,
            })

    categories = sorted({item["syntax_pattern"] for item in findings})
    return {
        "review_status": "completed",
        "review_type": "sql_syntax_review",
        "requires_application_context": True,
        "verified_application_vulnerability": False,
        "code_scan_excluded": True,
        "package_scan_allowed": False,
        "patterns": findings,
        "summary": {
            "total": len(findings),
            "patterns_detected": len(categories),
            "syntax_patterns": categories,
        },
    }