from dataclasses import dataclass
from pathlib import Path
from typing import List, Optional, Tuple, Union

from parsimonious import NodeVisitor  # type: ignore

from .scanner import scan
from .parser import parse_header


@dataclass
class Type:
    pass


@dataclass
class BasicType(Type):
    name: str


@dataclass
class PointerType(Type):
    target: Type


@dataclass
class ArrayType(Type):
    contents: Type
    size: int


@dataclass
class Declaration:
    name: str


@dataclass
class VariableDeclaration(Declaration):
    """Represents the declaration of a variable."""
    type: Type
    value: Optional[str]


@dataclass
class Declarations:
    included: List[Declaration]


@dataclass
class StructDeclaration(Declaration):
    """Represents the declaration of a struct type."""
    fields: Optional[List[VariableDeclaration]]


@dataclass
class EnumDeclaration(Declaration):
    """Represents the declaration of an enum type."""
    values: List[Tuple[str, Optional[int]]]


@dataclass
class UnionDeclaration(Declaration):
    """Represents the declaration of a union type."""
    tag: Optional[VariableDeclaration]
    cases: Union[List[VariableDeclaration], List[Tuple[str, Optional[VariableDeclaration]]]]


@dataclass
class FunctionDeclaration(Declaration):
    """Represents the declaration of a function."""
    return_type: Type
    args: List[VariableDeclaration]


# noinspection PyPep8Naming,PyMethodMayBeStatic,PyUnusedLocal
class DeclarationVisitor(NodeVisitor):
    def __init__(self, include_folders):
        self.data = []
        self.include_folders = include_folders

    def visit_HeaderFile(self, node, visited_children):
        includes, elements = visited_children
        return elements

    def visit_ImplementationFile(self, node, visited_children):
        includes, elements = visited_children
        includes = [y for x in includes for y in x]
        return [x for x in includes + elements if x is not None]

    def visit_IncludeStatement(self, node, visited_children):
        include, included_header, semicolon = visited_children
        assert include.text[0].type == 'include'
        assert included_header.type == 'string_literal'
        included_header = included_header.data.strip('"')
        assert semicolon.text[0].type == ';'
        for include_folder in self.include_folders:
            header = Path(include_folder) / included_header
            if header.exists():
                with open(header, 'r', encoding='utf-8') as header_file:
                    header_text = header_file.read()
                header_parse_tree = parse_header(scan(header_text))
                return self.visit(header_parse_tree)
        raise FileNotFoundError(included_header)

    def visit_NormalStructDefinition(self, node, visited_children):
        struct, name, lbrace, fields, rbrace = visited_children
        assert struct.text[0].type == 'struct'
        assert lbrace.text[0].type == '{'
        assert rbrace.text[0].type == '}'
        name = name.data
        if not isinstance(fields, list):
            fields = [fields]
        return StructDeclaration(name, fields)

    def visit_OpaqueStructDefinition(self, node, visited_children):
        opaque, struct, name, semi = visited_children
        assert opaque.text[0].type == 'opaque'
        assert struct.text[0].type == 'struct'
        assert semi.text[0].type == ';'
        name = name.data
        return StructDeclaration(name, None)

    def visit_EnumDefinition(self, node, visited_children):
        enum, name, lbrace, first_member, extra_members, trailing_comma, rbrace = visited_children
        assert enum.text[0].type == 'enum'
        assert lbrace.text[0].type == '{'
        assert rbrace.text[0].type == '}'
        name = name.data
        values = [first_member]
        for _, v in extra_members:
            values.append(v)
        return EnumDeclaration(name, values)

    def visit_EnumMember(self, node, visited_children):
        name, equals_value = visited_children
        name = name.data
        if not isinstance(equals_value, list):
            return name, None
        _, value = equals_value
        return name, value

    def visit_RobustUnionDefinition(self, node, visited_children):
        union, name, lbrace, tag, body, rbrace = visited_children
        assert union.text[0].type == 'union'
        assert lbrace.text[0].type == '{'
        assert rbrace.text[0].type == '}'
        name = name.data
        expected_tagname, body = body
        if tag.name != expected_tagname:
            raise NameError(f"tag {tag} does not match switch argument {expected_tagname}")
        if not isinstance(body, list):
            body = [body]
        return UnionDeclaration(name, tag, body)

    def visit_UnionBody(self, node, visited_children):
        switch, lparen, tag, rparen, lbrace, body, rbrace = visited_children
        assert switch.text[0].type == 'switch'
        assert lparen.text[0].type == '('
        assert rparen.text[0].type == ')'
        assert lbrace.text[0].type == '{'
        assert rbrace.text[0].type == '}'
        return tag.data, body

    def visit_UnionBodySet(self, node, visited_children):
        cases, var = visited_children
        if isinstance(cases, list):
            cases = cases[0]
        if isinstance(var, VariableDeclaration):
            return cases, var
        else:
            return cases, None

    def visit_CaseSpecifier(self, node, visited_children):
        while isinstance(visited_children, list) and len(visited_children) == 1:
            visited_children = visited_children[0]
        # TODO don't explode on 'default:'
        case, expr, colon = visited_children
        while isinstance(expr, list):
            expr = expr[0]
        # TODO don't explode on nontrivial expression
        return expr.data

    def visit_FragileUnionDefinition(self, node, visited_children):
        fragile, union, name, lbrace, body, rbrace = visited_children
        assert fragile.text[0].type == 'fragile'
        assert union.text[0].type == 'union'
        assert lbrace.text[0].type == '{'
        assert rbrace.text[0].type == '}'
        name = name.data
        return UnionDeclaration(name, None, body)

    def visit_FunctionDeclaration(self, node, visited_children):
        signature, semi = visited_children
        assert semi.text[0].type == ';'
        return signature

    def visit_VariableDefinition(self, node, visited_children):
        type, name, eq, value, semi = visited_children
        assert eq.text[0].type == '='
        assert semi.text[0].type == ';'
        name = name.data
        return VariableDeclaration(name, type, value)

    def visit_VariableDeclaration(self, node, visited_children):
        type, name, semi = visited_children
        assert semi.text[0].type == ';'
        name = name.data
        return VariableDeclaration(name, type, None)

    def visit_FunctionDefinition(self, node, visited_children):
        signature, body = visited_children
        return signature

    def visit_FunctionSignature(self, node, visited_children):
        return_type, name, lparen, args, rparen = visited_children
        assert name.type == 'identifier'
        name = name.data
        assert lparen.text[0].type == '('
        assert rparen.text[0].type == ')'
        return FunctionDeclaration(name, return_type, args)

    def visit_BasicType(self, node, visited_children):
        while isinstance(visited_children, list) and len(visited_children) == 1:
            visited_children = visited_children[0]
        if isinstance(visited_children, list):
            if len(visited_children) == 3:
                # parenthesized!
                lparen, ty, rparen = visited_children
                assert lparen.text[0].type == '('
                assert rparen.text[0].type == ')'
                return ty
            else:
                category, name = visited_children
                category = category.text[0].type
                name = name.data
                return BasicType(f"{category} {name}")
        return BasicType(visited_children.text[0].type)

    def visit_ArrayType(self, node, visited_children):
        contents, lbracket, size, rbracket = visited_children
        assert lbracket.text[0].type == '['
        assert rbracket.text[0].type == ']'
        # TODO don't explode on nontrivial expression
        while isinstance(size, list):
            size = size[0]
        size = int(size.data)
        return ArrayType(contents, size)

    def visit_PointerType(self, node, visited_children):
        contents, splat = visited_children
        assert splat.text[0].type == '*'
        return PointerType(contents)

    def visit_constant(self, node, visited_children):
        return node.text[0]

    def visit_string_literal(self, node, visited_children):
        return node.text[0]

    def visit_identifier(self, node, visited_children):
        return node.text[0]

    def generic_visit(self, node, visited_children):
        """ The generic visit method. """
        if not visited_children:
            return node
        if len(visited_children) == 1:
            return visited_children[0]
        return visited_children


def load_declarations(parse_tree, include_dirs):
    declarations = DeclarationVisitor(include_dirs)
    return declarations.visit(parse_tree)