"""
GPT parsing module.

The GPT markdown files have to adhere to a very specific format described in the README.md file in the root of the CSP project.
"""

import os, re
from collections import namedtuple
from typing import Union, Tuple, Generator

compiled_pattern = re.compile(r'^([0-9a-z]{9})_([^\.]+)\.md$', re.IGNORECASE)

GPT_BASE_URL = 'https://chat.openai.com/g/g-'
GPT_BASE_URL_L = len(GPT_BASE_URL)
FIELD_PREFIX = 'GPT'

GPT_FILE_VERSION_RE = re.compile(r'\[([^]]*)\]\.md$', re.IGNORECASE)

GptFieldInfo = namedtuple('FieldInfo', ['order', 'display'])

GptIdentifier = namedtuple('GptIdentifier', ['id', 'name'])
"""Description of the fields supported by GPT markdown files."""

SUPPORTED_FIELDS = {
    'url':              GptFieldInfo(10, 'URL'),
    'title':            GptFieldInfo(20, 'Title'),
    'description':      GptFieldInfo(30, 'Description'),
    'logo':             GptFieldInfo(40, 'Logo'),
    'verif_status':     GptFieldInfo(50, 'Verification Status'),
    'instructions':     GptFieldInfo(60, 'Instructions'),
    'actions':          GptFieldInfo(70, 'Actions'),
    'kb_files_list':    GptFieldInfo(80, 'KB Files List'),
    'extras':           GptFieldInfo(90, 'Extras')
}
"""
Dictionary of the fields supported by GPT markdown files:
- The key should always be in lower case
- The GPT markdown file will have the form: {FIELD_PREFIX} {key}: {value}
"""

class GptMarkdownFile:
    """
    A class to represent a GPT markdown file.
    """
    def __init__(self, fields={}, filename: str = '') -> None:
        self.fields = fields
        self.filename = filename

    def get(self, key: str, strip: bool = True) -> Union[str, None]:
        """
        Return the value of the field with the specified key.
        :param key: str, key of the field.
        :return: str, value of the field.
        """
        key = key.lower()
        if key == 'version':
            m = GPT_FILE_VERSION_RE.search(self.filename)
            return m.group(1) if m else ''

        v = self.fields.get(key)
        return v.strip() if strip else v
    
    def id(self) -> Union[GptIdentifier, None]:
        """
        Return the GPT identifier.
        :return: GptIdentifier object.
        """
        return parse_gpturl(self.fields.get('url'))
            
    def __str__(self) -> str:
        sorted_fields = sorted(self.fields.items(), key=lambda x: SUPPORTED_FIELDS[x[0]].order)
        # Check if the field value contains the start marker of the markdown block and add a blank line before it
        field_strings = []
        for key, value in sorted_fields:
            if value:
                # Only replace the first occurrence of ```markdown
                modified_value = value.replace("```markdown", "\r\n```markdown", 1)
                field_string = f"{FIELD_PREFIX} {SUPPORTED_FIELDS[key].display}: {modified_value}"
                field_strings.append(field_string)
        return "\r\n".join(field_strings)

    @staticmethod
    def parse(file_path: str) -> Union['GptMarkdownFile', Tuple[bool, str]]:
        """
        Parse a markdown file and return a GptMarkdownFile object.
        :param file_path: str, path to the markdown file.
        :return: GptMarkdownFile if successful, otherwise a tuple with False and an error message.
        """
        if not os.path.exists(file_path):
            return (False, f"File '{file_path}' does not exist.")

        with open(file_path, 'r', encoding='utf-8') as file:
            fields = {key.lower(): [] for key in SUPPORTED_FIELDS.keys()}
            field_re = re.compile(f"^\s*{FIELD_PREFIX}\s+({'|'.join(fields.keys())}):", re.IGNORECASE)
            current_field = None
            for line in file:
                if m := field_re.match(line):
                    current_field = m.group(1).lower()
                    line = line[len(m.group(0)):].strip()

                if current_field:
                    if current_field not in SUPPORTED_FIELDS:
                        return (False, f"Field '{current_field}' is not supported.")

                    fields[current_field].append(line)

        gpt = GptMarkdownFile(
            {key: ''.join(value) for key, value in fields.items()},
            filename=file_path)
        return (True, gpt)

    def save(self, file_path: str) -> Tuple[bool, Union[str, None]]:
        """
        Save the GptMarkdownFile object to a markdown file.
        :param file_path: str, path to the markdown file.
        """
        try:
            with open(file_path, 'w', encoding='utf-8') as file:
                file.write(str(self))
            return (True, None)
        except Exception as e:
            return (False, f"Failed to save file '{file_path}': {e}")

def parse_gpturl(url: str) -> Union[GptIdentifier, None]:
    if url and url.startswith(GPT_BASE_URL):
        id = url[GPT_BASE_URL_L:].split('\n')[0]
        i = id.find('-')
        if i != -1:
            return GptIdentifier(id[:i], id[i+1:])
        else:
            return GptIdentifier(id, '')


def get_prompts_path() -> str:
    """Return the path to the prompts directory."""
    return os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'prompts', 'gpts'))

def enum_gpts() -> Generator[Tuple[bool, Union[GptMarkdownFile, str]], None, None]:
    """Enumerate all the GPT files in the prompts directory, parse them and return the parsed GPT object."""
    prompts_path = get_prompts_path()
    for file_path in os.listdir(prompts_path):
        _, ext = os.path.splitext(file_path)
        if ext != '.md':
            continue
        file_path = os.path.join(prompts_path, file_path)
        ok, gpt = GptMarkdownFile.parse(file_path)
        if ok:
            yield (True, gpt)
        else:
            yield (False, f"Failed to parse '{file_path}': {gpt}")

def enum_gpt_files() -> Generator[str, None, None]:
    """
    Enumerate all the GPT files in the prompts directory while relying on the files naming convention.
    To normalize all the GPT file names, run the `idxtool.py --rename`
    """
    pattern = r'[a-z]{9}_[a-z]+\.[a-z]+'

    prompts_path = get_prompts_path()
    for file_path in os.listdir(prompts_path):
        _, ext = os.path.splitext(file_path)
        if ext != '.md':
            continue
        file_path = os.path.join(prompts_path, file_path)
        yield file_path