import t, c
from stdint import *
import ast
import string
import memhub


# ============================================================
# StubGen.Converter - pyi 存根文件生成器
#
# 从 AST 直接生成 .pyi 存根文件，不依赖 CPython 的 PythonToStubConverter。
# 遍历 Module 节点的 children，提取函数签名、类定义、变量声明、
# import 语句，生成 Python 类型存根文件。
#
# 本文件使用 Viper 语法实现，可被 TPC 编译为原生码。
# ============================================================


# ============================================================
# _PyiEmit - 追加字符串到缓冲区
#
# 将 text 追加到 buf 的 pos 位置，返回新的 pos。
# 自动处理缓冲区溢出（截断）。
# ============================================================
def _PyiEmit(buf: bytes, buf_size: t.CSizeT, pos: t.CSizeT,
             text: str) -> t.CSizeT:
    """追加 text 到 buf 的 pos 位置，返回新的 pos"""
    if buf is None or text is None or pos >= buf_size:
        return pos
    tlen: t.CSizeT = string.strlen(text)
    if tlen == 0:
        return pos
    remain: t.CSizeT = buf_size - pos
    if tlen >= remain:
        tlen = remain - 1
    if tlen > 0:
        string.memcpy(buf + pos, text, tlen)
    return pos + tlen


# ============================================================
# _PyiIndent - 追加缩进空格
#
# 追加 level*4 个空格到 buf 的 pos 位置。
# ============================================================
def _PyiIndent(buf: bytes, buf_size: t.CSizeT, pos: t.CSizeT,
               level: int) -> t.CSizeT:
    """追加 level*4 个空格到 buf，返回新的 pos"""
    i: int = 0
    while i < level:
        pos = _PyiEmit(buf, buf_size, pos, "    ")
        i += 1
    return pos


# ============================================================
# _PyiTypeStr - 递归生成类型注解字符串
#
# 将 AST 类型注解节点转换为字符串表示，写入 buf 的 pos 位置。
# 支持: Name, Attribute, Subscript, BinOp(|), Constant(前向引用), Tuple
# ============================================================
def _PyiTypeStr(buf: bytes, buf_size: t.CSizeT, pos: t.CSizeT,
                annot: ast.AST | t.CPtr) -> t.CSizeT:
    """递归生成类型注解字符串，返回新的 pos"""
    if annot is None:
        return _PyiEmit(buf, buf_size, pos, "t.CInt")

    k: int = annot.kind()

    # Name: 简单类型名 (如 int, str, MyClass)
    if k == ast.ASTKind.Name:
        nm: ast.Name | t.CPtr = (ast.Name | t.CPtr)(annot)
        if nm.id is not None:
            return _PyiEmit(buf, buf_size, pos, nm.id)
        return _PyiEmit(buf, buf_size, pos, "t.CInt")

    # Attribute: 属性引用 (如 t.CInt, memhub.MemBuddy)
    if k == ast.ASTKind.Attribute:
        at: ast.Attribute | t.CPtr = (ast.Attribute | t.CPtr)(annot)
        pos = _PyiTypeStr(buf, buf_size, pos, at.value)
        pos = _PyiEmit(buf, buf_size, pos, ".")
        if at.attr is not None:
            pos = _PyiEmit(buf, buf_size, pos, at.attr)
        return pos

    # Subscript: 下标类型 (如 list[int], t.CArray[elem, count])
    if k == ast.ASTKind.Subscript:
        sub: ast.Subscript | t.CPtr = (ast.Subscript | t.CPtr)(annot)
        pos = _PyiTypeStr(buf, buf_size, pos, sub.value)
        pos = _PyiEmit(buf, buf_size, pos, "[")
        pos = _PyiTypeStr(buf, buf_size, pos, sub.slice)
        pos = _PyiEmit(buf, buf_size, pos, "]")
        return pos

    # BinOp: 联合类型 (如 int | str, File | t.CPtr)
    if k == ast.ASTKind.BinOp:
        bop: ast.BinOp | t.CPtr = (ast.BinOp | t.CPtr)(annot)
        pos = _PyiTypeStr(buf, buf_size, pos, bop.left)
        pos = _PyiEmit(buf, buf_size, pos, " | ")
        pos = _PyiTypeStr(buf, buf_size, pos, bop.right)
        return pos

    # Constant: 字符串前向引用 (如 'MyClass') 或 None
    if k == ast.ASTKind.Constant:
        cn: ast.Constant | t.CPtr = (ast.Constant | t.CPtr)(annot)
        if cn.const_kind == ast.CONST_STR:
            pos = _PyiEmit(buf, buf_size, pos, "'")
            if cn.str_val is not None:
                pos = _PyiEmit(buf, buf_size, pos, cn.str_val)
            pos = _PyiEmit(buf, buf_size, pos, "'")
            return pos
        if cn.const_kind == ast.CONST_NONE:
            return _PyiEmit(buf, buf_size, pos, "None")
        return _PyiEmit(buf, buf_size, pos, "t.CInt")

    # Tuple: 多参数下标 (如 Dict[str, int])
    if k == ast.ASTKind.Tuple:
        tup: ast.Tuple | t.CPtr = (ast.Tuple | t.CPtr)(annot)
        if tup.elts is not None:
            tn: t.CSizeT = tup.elts.__len__()
            ti: t.CSizeT = 0
            while ti < tn:
                if ti > 0:
                    pos = _PyiEmit(buf, buf_size, pos, ", ")
                el: ast.AST | t.CPtr = tup.elts.get(ti)
                pos = _PyiTypeStr(buf, buf_size, pos, el)
                ti += 1
        return pos

    # 未知类型，回退到 t.CInt
    return _PyiEmit(buf, buf_size, pos, "t.CInt")


# ============================================================
# _PyiFunction - 生成函数签名
#
# 格式: def name(param: Type, ...) -> ReturnType: pass
# ============================================================
def _PyiFunction(buf: bytes, buf_size: t.CSizeT, pos: t.CSizeT,
                 fn: ast.FunctionDef | t.CPtr,
                 indent_level: int, class_name: str) -> t.CSizeT:
    """生成函数签名到 buf，返回新的 pos"""
    pos = _PyiIndent(buf, buf_size, pos, indent_level)
    pos = _PyiEmit(buf, buf_size, pos, "def ")
    if fn.name is not None:
        pos = _PyiEmit(buf, buf_size, pos, fn.name)
    pos = _PyiEmit(buf, buf_size, pos, "(")

    # 参数列表
    args_node: ast.AST | t.CPtr = fn.args
    if args_node is not None:
        args: ast.Arguments | t.CPtr = (ast.Arguments | t.CPtr)(args_node)
        first: int = 1

        # 位置参数
        if args.args is not None:
            an: t.CSizeT = args.args.__len__()
            ai: t.CSizeT = 0
            while ai < an:
                if first == 0:
                    pos = _PyiEmit(buf, buf_size, pos, ", ")
                first = 0
                ag: ast.Arg | t.CPtr = (ast.Arg | t.CPtr)(args.args.get(ai))
                if ag.arg is not None:
                    pos = _PyiEmit(buf, buf_size, pos, ag.arg)
                if ag.annotation is not None:
                    pos = _PyiEmit(buf, buf_size, pos, ": ")
                    pos = _PyiTypeStr(buf, buf_size, pos, ag.annotation)
                ai += 1

        # *args
        if args.vararg is not None:
            if first == 0:
                pos = _PyiEmit(buf, buf_size, pos, ", ")
            first = 0
            pos = _PyiEmit(buf, buf_size, pos, "*")
            va: ast.Arg | t.CPtr = (ast.Arg | t.CPtr)(args.vararg)
            if va.arg is not None:
                pos = _PyiEmit(buf, buf_size, pos, va.arg)

        # **kwargs
        if args.kwarg is not None:
            if first == 0:
                pos = _PyiEmit(buf, buf_size, pos, ", ")
            first = 0
            pos = _PyiEmit(buf, buf_size, pos, "**")
            kw: ast.Arg | t.CPtr = (ast.Arg | t.CPtr)(args.kwarg)
            if kw.arg is not None:
                pos = _PyiEmit(buf, buf_size, pos, kw.arg)

    pos = _PyiEmit(buf, buf_size, pos, ")")

    # 返回类型
    if fn.returns is not None:
        pos = _PyiEmit(buf, buf_size, pos, " -> ")
        pos = _PyiTypeStr(buf, buf_size, pos, fn.returns)

    pos = _PyiEmit(buf, buf_size, pos, ": pass\n")
    return pos


# ============================================================
# _PyiClass - 生成类定义
#
# 格式:
#   class Name(Base):
#       field: Type
#       def method(self: Name, ...) -> RetType: pass
# ============================================================
def _PyiClass(buf: bytes, buf_size: t.CSizeT, pos: t.CSizeT,
              cls: ast.ClassDef | t.CPtr, indent_level: int) -> t.CSizeT:
    """生成类定义到 buf，返回新的 pos"""
    pos = _PyiIndent(buf, buf_size, pos, indent_level)
    pos = _PyiEmit(buf, buf_size, pos, "class ")
    if cls.name is not None:
        pos = _PyiEmit(buf, buf_size, pos, cls.name)

    # 基类
    if cls.bases is not None:
        bn: t.CSizeT = cls.bases.__len__()
        if bn > 0:
            pos = _PyiEmit(buf, buf_size, pos, "(")
            bi: t.CSizeT = 0
            while bi < bn:
                if bi > 0:
                    pos = _PyiEmit(buf, buf_size, pos, ", ")
                base: ast.AST | t.CPtr = cls.bases.get(bi)
                pos = _PyiTypeStr(buf, buf_size, pos, base)
                bi += 1
            pos = _PyiEmit(buf, buf_size, pos, ")")

    pos = _PyiEmit(buf, buf_size, pos, ":\n")

    # 类成员
    has_member: int = 0

    if cls.children is not None:
        cn: t.CSizeT = cls.children.__len__()
        ci: t.CSizeT = 0
        while ci < cn:
            stmt: ast.AST | t.CPtr = cls.children.get(ci)
            if stmt is not None:
                sk: int = stmt.kind()

                # 方法
                if sk == ast.ASTKind.FunctionDef:
                    mfn: ast.FunctionDef | t.CPtr = (ast.FunctionDef | t.CPtr)(stmt)
                    pos = _PyiFunction(buf, buf_size, pos, mfn, indent_level + 1, cls.name)
                    has_member = 1

                # 带注解的属性
                elif sk == ast.ASTKind.AnnAssign:
                    aa: ast.AnnAssign | t.CPtr = (ast.AnnAssign | t.CPtr)(stmt)
                    if aa.target is not None and aa.target.kind() == ast.ASTKind.Name:
                        tn: ast.Name | t.CPtr = (ast.Name | t.CPtr)(aa.target)
                        pos = _PyiIndent(buf, buf_size, pos, indent_level + 1)
                        if tn.id is not None:
                            pos = _PyiEmit(buf, buf_size, pos, tn.id)
                        pos = _PyiEmit(buf, buf_size, pos, ": ")
                        pos = _PyiTypeStr(buf, buf_size, pos, aa.annotation)
                        pos = _PyiEmit(buf, buf_size, pos, "\n")
                        has_member = 1
            ci += 1

    # 空类补 pass
    if has_member == 0:
        pos = _PyiIndent(buf, buf_size, pos, indent_level + 1)
        pos = _PyiEmit(buf, buf_size, pos, "pass\n")

    pos = _PyiEmit(buf, buf_size, pos, "\n")
    return pos


# ============================================================
# _GeneratePyiFromAst - 从 AST 生成 .pyi 存根文件
#
# 遍历 AST Module 节点，提取函数签名、类定义、变量声明、import 语句，
# 生成 Python 类型存根文件内容到 buf。
#
# Args:
#   mb: 内存池（保留以符合调用约定，实际未使用）
#   tree: AST Module 根节点
#   rel_path: 相对路径（用于模块名，当前未使用）
#   buf: 输出缓冲区
#   buf_size: 缓冲区大小
#
# Returns:
#   写入的字节数（0 表示失败）
# ============================================================
def _GeneratePyiFromAst(mb: memhub.MemBuddy | t.CPtr, tree: ast.AST | t.CPtr,
                        rel_path: str, buf: bytes,
                        buf_size: t.CSizeT) -> t.CSizeT:
    """从 AST 生成 .pyi 存根文件内容到 buf"""
    if tree is None or buf is None or buf_size == 0:
        return 0

    pos: t.CSizeT = 0

    # 文件头
    pos = _PyiEmit(buf, buf_size, pos, "\"\"\"Auto-generated Python stub file\"\"\"\n\n")

    if tree.children is None:
        if pos < buf_size:
            buf[pos] = 0
        return pos

    n: t.CSizeT = tree.children.__len__()

    # 第一遍扫描：检测 import t/c
    has_import_t: int = 0
    has_import_c: int = 0
    i: t.CSizeT = 0
    while i < n:
        stmt: ast.AST | t.CPtr = tree.children.get(i)
        if stmt is not None and stmt.kind() == ast.ASTKind.Import:
            imp: ast.Import | t.CPtr = (ast.Import | t.CPtr)(stmt)
            if imp.names is not None:
                an: t.CSizeT = imp.names.__len__()
                ai: t.CSizeT = 0
                while ai < an:
                    al: ast.Alias | t.CPtr = (ast.Alias | t.CPtr)(imp.names.get(ai))
                    if al is not None and al.name is not None:
                        if string.strcmp(al.name, "t") == 0:
                            has_import_t = 1
                        elif string.strcmp(al.name, "c") == 0:
                            has_import_c = 1
                    ai += 1
        i += 1

    # 补充缺失的 import t/c
    if has_import_t == 0 and has_import_c == 0:
        pos = _PyiEmit(buf, buf_size, pos, "import t, c\n\n")
    elif has_import_t == 0:
        pos = _PyiEmit(buf, buf_size, pos, "import t\n\n")
    elif has_import_c == 0:
        pos = _PyiEmit(buf, buf_size, pos, "import c\n\n")
    else:
        pos = _PyiEmit(buf, buf_size, pos, "\n")

    # 第二遍扫描：生成声明
    i = 0
    while i < n:
        stmt = tree.children.get(i)
        if stmt is not None:
            k: int = stmt.kind()

            # Import 语句
            if k == ast.ASTKind.Import:
                imp2: ast.Import | t.CPtr = (ast.Import | t.CPtr)(stmt)
                pos = _PyiEmit(buf, buf_size, pos, "import ")
                if imp2.names is not None:
                    an2: t.CSizeT = imp2.names.__len__()
                    ai2: t.CSizeT = 0
                    while ai2 < an2:
                        if ai2 > 0:
                            pos = _PyiEmit(buf, buf_size, pos, ", ")
                        al2: ast.Alias | t.CPtr = (ast.Alias | t.CPtr)(imp2.names.get(ai2))
                        if al2 is not None and al2.name is not None:
                            pos = _PyiEmit(buf, buf_size, pos, al2.name)
                            if al2.asname is not None and string.strlen(al2.asname) > 0:
                                pos = _PyiEmit(buf, buf_size, pos, " as ")
                                pos = _PyiEmit(buf, buf_size, pos, al2.asname)
                        ai2 += 1
                pos = _PyiEmit(buf, buf_size, pos, "\n")

            # ImportFrom 语句
            elif k == ast.ASTKind.ImportFrom:
                ifr: ast.ImportFrom | t.CPtr = (ast.ImportFrom | t.CPtr)(stmt)
                pos = _PyiEmit(buf, buf_size, pos, "from ")
                lvl: int = ifr.level
                while lvl > 0:
                    pos = _PyiEmit(buf, buf_size, pos, ".")
                    lvl -= 1
                if ifr.module is not None:
                    pos = _PyiEmit(buf, buf_size, pos, ifr.module)
                pos = _PyiEmit(buf, buf_size, pos, " import ")
                if ifr.names is not None:
                    an3: t.CSizeT = ifr.names.__len__()
                    ai3: t.CSizeT = 0
                    while ai3 < an3:
                        if ai3 > 0:
                            pos = _PyiEmit(buf, buf_size, pos, ", ")
                        al3: ast.Alias | t.CPtr = (ast.Alias | t.CPtr)(ifr.names.get(ai3))
                        if al3 is not None and al3.name is not None:
                            pos = _PyiEmit(buf, buf_size, pos, al3.name)
                            if al3.asname is not None and string.strlen(al3.asname) > 0:
                                pos = _PyiEmit(buf, buf_size, pos, " as ")
                                pos = _PyiEmit(buf, buf_size, pos, al3.asname)
                        ai3 += 1
                pos = _PyiEmit(buf, buf_size, pos, "\n")

            # 函数定义
            elif k == ast.ASTKind.FunctionDef:
                fn: ast.FunctionDef | t.CPtr = (ast.FunctionDef | t.CPtr)(stmt)
                pos = _PyiFunction(buf, buf_size, pos, fn, 0, "")
                pos = _PyiEmit(buf, buf_size, pos, "\n")

            # 类定义
            elif k == ast.ASTKind.ClassDef:
                cls: ast.ClassDef | t.CPtr = (ast.ClassDef | t.CPtr)(stmt)
                pos = _PyiClass(buf, buf_size, pos, cls, 0)

            # 带注解的变量声明
            elif k == ast.ASTKind.AnnAssign:
                aa: ast.AnnAssign | t.CPtr = (ast.AnnAssign | t.CPtr)(stmt)
                if aa.target is not None and aa.target.kind() == ast.ASTKind.Name:
                    nm: ast.Name | t.CPtr = (ast.Name | t.CPtr)(aa.target)
                    if nm.id is not None:
                        pos = _PyiEmit(buf, buf_size, pos, nm.id)
                        pos = _PyiEmit(buf, buf_size, pos, ": ")
                        pos = _PyiTypeStr(buf, buf_size, pos, aa.annotation)
                        pos = _PyiEmit(buf, buf_size, pos, "\n")

        i += 1

    # NUL 终止
    if pos < buf_size:
        buf[pos] = 0
    else:
        buf[buf_size - 1] = 0
    return pos