from __future__ import annotations

import re
import sys
from dataclasses import dataclass
from pathlib import Path


ROOT = Path(__file__).resolve().parents[1]
GAS_FILES = sorted(ROOT.glob("gas*.gs"))


@dataclass
class FunctionDef:
    name: str
    min_arity: int
    max_arity: int
    path: Path
    line: int


@dataclass
class CallSite:
    name: str
    arity: int
    path: Path
    line: int


def sanitize_js(text: str) -> str:
    out: list[str] = []
    i = 0
    n = len(text)
    state = "normal"
    while i < n:
        ch = text[i]
        nxt = text[i + 1] if i + 1 < n else ""
        if state == "normal":
            if ch == "/" and nxt == "/":
                out.extend("  ")
                i += 2
                state = "line_comment"
                continue
            if ch == "/" and nxt == "*":
                out.extend("  ")
                i += 2
                state = "block_comment"
                continue
            if ch == "'":
                out.append(" ")
                i += 1
                state = "single_quote"
                continue
            if ch == '"':
                out.append(" ")
                i += 1
                state = "double_quote"
                continue
            if ch == "`":
                out.append(" ")
                i += 1
                state = "template"
                continue
            out.append(ch)
            i += 1
            continue
        if state == "line_comment":
            if ch == "\n":
                out.append("\n")
                state = "normal"
            else:
                out.append(" ")
            i += 1
            continue
        if state == "block_comment":
            if ch == "*" and nxt == "/":
                out.extend("  ")
                i += 2
                state = "normal"
            else:
                out.append("\n" if ch == "\n" else " ")
                i += 1
            continue
        if state in {"single_quote", "double_quote", "template"}:
            if ch == "\\":
                out.append("S")
                if i + 1 < n:
                    out.append("S" if text[i + 1] != "\n" else "\n")
                i += 2
                continue
            if (state == "single_quote" and ch == "'") or (
                state == "double_quote" and ch == '"'
            ) or (state == "template" and ch == "`"):
                out.append(" ")
                i += 1
                state = "normal"
            else:
                out.append("\n" if ch == "\n" else "S")
                i += 1
            continue
    return "".join(out)


def line_of(text: str, index: int) -> int:
    return text.count("\n", 0, index) + 1


def find_matching(text: str, start: int, opener: str, closer: str) -> int:
    depth = 0
    for idx in range(start, len(text)):
        ch = text[idx]
        if ch == opener:
            depth += 1
        elif ch == closer:
            depth -= 1
            if depth == 0:
                return idx
    return -1


def count_arguments(chunk: str) -> int:
    if not chunk.strip():
        return 0
    depth_paren = 0
    depth_brace = 0
    depth_bracket = 0
    count = 1
    for ch in chunk:
        if ch == "(":
            depth_paren += 1
        elif ch == ")":
            depth_paren -= 1
        elif ch == "{":
            depth_brace += 1
        elif ch == "}":
            depth_brace -= 1
        elif ch == "[":
            depth_bracket += 1
        elif ch == "]":
            depth_bracket -= 1
        elif ch == "," and depth_paren == 0 and depth_brace == 0 and depth_bracket == 0:
            count += 1
    return count


def parse_param_bounds(params: str) -> tuple[int, int]:
    tokens = [p.strip() for p in params.split(",") if p.strip()]
    if not tokens:
        return 0, 0
    min_arity = 0
    max_arity = len(tokens)
    for token in tokens:
        if "=" not in token and not token.startswith("..."):
            min_arity += 1
    return min_arity, max_arity


def extract_function_defs(path: Path) -> list[FunctionDef]:
    raw = path.read_text(encoding="utf-8")
    text = sanitize_js(raw)
    defs: list[FunctionDef] = []
    for match in re.finditer(r"\bfunction\s+([A-Za-z_$][\w$]*)\s*\(", text):
        name = match.group(1)
        open_idx = text.find("(", match.start())
        close_idx = find_matching(text, open_idx, "(", ")")
        if close_idx == -1:
            continue
        params = text[open_idx + 1 : close_idx]
        min_arity, max_arity = parse_param_bounds(params)
        defs.append(
            FunctionDef(
                name=name,
                min_arity=min_arity,
                max_arity=max_arity,
                path=path,
                line=line_of(raw, match.start()),
            )
        )
    return defs


def extract_calls(path: Path, function_names: set[str]) -> list[CallSite]:
    raw = path.read_text(encoding="utf-8")
    text = sanitize_js(raw)
    calls: list[CallSite] = []
    for name in sorted(function_names):
        pattern = re.compile(rf"\b{re.escape(name)}\s*\(")
        for match in pattern.finditer(text):
            prefix = text[max(0, match.start() - 16) : match.start()]
            if re.search(r"\bfunction\s+$", prefix):
                continue
            open_idx = text.find("(", match.start())
            close_idx = find_matching(text, open_idx, "(", ")")
            if close_idx == -1:
                continue
            args = text[open_idx + 1 : close_idx]
            calls.append(CallSite(name=name, arity=count_arguments(args), path=path, line=line_of(raw, match.start())))
    return calls


def main() -> int:
    if not GAS_FILES:
        print("No gas*.gs files found.")
        return 1

    defs: list[FunctionDef] = []
    for path in GAS_FILES:
        defs.extend(extract_function_defs(path))

    def_map = {item.name: item for item in defs}
    errors: list[str] = []
    for path in GAS_FILES:
        for call in extract_calls(path, set(def_map)):
            defined = def_map.get(call.name)
            if defined is None:
                continue
            if not (defined.min_arity <= call.arity <= defined.max_arity):
                errors.append(
                    f"{path.name}:{call.line}: {call.name} call arity={call.arity} "
                    f"outside definition range={defined.min_arity}..{defined.max_arity} "
                    f"at {defined.path.name}:{defined.line}"
                )

    if errors:
        print("GAS CALL ARITY VALIDATION FAILED")
        for err in errors:
            print(f"- {err}")
        return 1

    print(f"GAS CALL ARITY OK: checked {len(def_map)} functions across {len(GAS_FILES)} files")
    return 0


if __name__ == "__main__":
    sys.exit(main())