from typing import TYPE_CHECKING

from .utils.constants import JSONReturnType
from .utils.json_context import ContextValues

if TYPE_CHECKING:
    from .json_parser import JSONParser


def parse_comment(self: "JSONParser") -> JSONReturnType:
    """
    Parse code-like comments:

    - "# comment": A line comment that continues until a newline.
    - "// comment": A line comment that continues until a newline.
    - "/* comment */": A block comment that continues until the closing delimiter "*/".

    The comment is skipped over and an empty string is returned so that comments do not interfere
    with the actual JSON elements.
    """
    while True:
        char = self.get_char_at()
        termination_characters = ["\n", "\r"]
        if ContextValues.ARRAY in self.context.context:
            termination_characters.append("]")
        if ContextValues.OBJECT_VALUE in self.context.context:
            termination_characters.append("}")
        if ContextValues.OBJECT_KEY in self.context.context:
            termination_characters.append(":")
        # Line comment starting with #
        if char == "#":
            comment = ""
            while char and char not in termination_characters:
                comment += char
                self.index += 1
                char = self.get_char_at()
            self.log(f"Found line comment: {comment}, ignoring")
        # Comments starting with '/'
        elif char == "/":
            next_char = self.get_char_at(1)
            # Handle line comment starting with //
            if next_char == "/":
                comment = "//"
                self.index += 2  # Skip both slashes.
                char = self.get_char_at()
                while char and char not in termination_characters:
                    comment += char
                    self.index += 1
                    char = self.get_char_at()
                self.log(f"Found line comment: {comment}, ignoring")
            # Handle block comment starting with /*
            elif next_char == "*":
                comment = "/*"
                self.index += 2  # Skip '/*'
                while True:
                    char = self.get_char_at()
                    if not char:
                        self.log("Reached end-of-string while parsing block comment; unclosed block comment.")
                        break
                    comment += char
                    self.index += 1
                    if comment.endswith("*/"):
                        break
                self.log(f"Found block comment: {comment}, ignoring")
            else:
                # Skip standalone '/' characters that are not part of a comment
                # to avoid getting stuck in an infinite loop
                self.index += 1
        if self.context.empty:
            # Avoid a parse_json -> parse_comment -> parse_json chain for long runs of
            # top-level comments; re-enter only once after we have consumed them all.
            self.skip_whitespaces()
            if self.get_char_at() in ["#", "/"]:
                continue
            return self.parse_json()
        break
    return ""