from collections import namedtuple
from dataclasses import dataclass
from datetime import datetime
from typing import Optional, Tuple
from urllib.parse import urlparse

from github import AppAuthentication, File, Github

from pr_agent.config_loader import settings

@dataclass
class FilePatchInfo:
    base_file: str
    head_file: str
    patch: str
    filename: str
    tokens: int = -1

class GithubProvider:
    def __init__(self, pr_url: Optional[str] = None, installation_id: Optional[int] = None):
        self.installation_id = installation_id
        self.github_client = self._get_github_client()
        self.repo = None
        self.pr_num = None
        self.pr = None
        if pr_url:
            self.set_pr(pr_url)

    def set_pr(self, pr_url: str):
        self.repo, self.pr_num = self._parse_pr_url(pr_url)
        self.pr = self._get_pr()

    def get_diff_files(self) -> list[FilePatchInfo]:
        files = self.pr.get_files()
        diff_files = []
        for file in files:
            original_file_content_str = self._get_pr_file_content(file, self.pr.base.sha)
            new_file_content_str = self._get_pr_file_content(file, self.pr.head.sha)
            diff_files.append(FilePatchInfo(original_file_content_str, new_file_content_str, file.patch, file.filename))
        return diff_files

    def publish_comment(self, pr_comment: str):
        self.pr.create_issue_comment(pr_comment)

    def get_title(self):
        return self.pr.title

    def get_description(self):
        return self.pr.body

    def get_languages(self):
        return self._get_repo().get_languages()

    def get_main_pr_language(self) -> str:
        """
        Get the main language of the commit. Return an empty string if cannot determine.
        """
        main_language_str = ""
        try:
            languages = self.get_languages()
            top_language = max(languages, key=languages.get).lower()

            # validate that the specific commit uses the main language
            extension_list = []
            files = self.pr.get_files()
            for file in files:
                extension_list.append(file.filename.rsplit('.')[-1])

            # get the most common extension
            most_common_extension = max(set(extension_list), key=extension_list.count)

            # look for a match. TBD: add more languages, do this systematically
            if most_common_extension == 'py' and top_language == 'python' or \
                    most_common_extension == 'js' and top_language == 'javascript' or \
                    most_common_extension == 'ts' and top_language == 'typescript' or \
                    most_common_extension == 'go' and top_language == 'go' or \
                    most_common_extension == 'java' and top_language == 'java' or \
                    most_common_extension == 'c' and top_language == 'c' or \
                    most_common_extension == 'cpp' and top_language == 'c++' or \
                    most_common_extension == 'cs' and top_language == 'c#' or \
                    most_common_extension == 'swift' and top_language == 'swift' or \
                    most_common_extension == 'php' and top_language == 'php' or \
                    most_common_extension == 'rb' and top_language == 'ruby' or \
                    most_common_extension == 'rs' and top_language == 'rust' or \
                    most_common_extension == 'scala' and top_language == 'scala' or \
                    most_common_extension == 'kt' and top_language == 'kotlin' or \
                    most_common_extension == 'pl' and top_language == 'perl' or \
                    most_common_extension == 'swift' and top_language == 'swift':
                main_language_str = top_language

        except Exception:
            pass

        return main_language_str

    def get_pr_branch(self):
        return self.pr.head.ref

    def get_notifications(self, since: datetime):
        deployment_type = settings.get("GITHUB.DEPLOYMENT_TYPE", "user")

        if deployment_type != 'user':
            raise ValueError("Deployment mode must be set to 'user' to get notifications")

        notifications = self.github_client.get_user().get_notifications(since=since)
        return notifications

    @staticmethod
    def _parse_pr_url(pr_url: str) -> Tuple[str, int]:
        parsed_url = urlparse(pr_url)

        if 'github.com' not in parsed_url.netloc:
            raise ValueError("The provided URL is not a valid GitHub URL")

        path_parts = parsed_url.path.strip('/').split('/')
        if 'api.github.com' in parsed_url.netloc:
            if len(path_parts) < 5 or path_parts[3] != 'pulls':
                raise ValueError("The provided URL does not appear to be a GitHub PR URL")
            repo_name = '/'.join(path_parts[1:3])
            try:
                pr_number = int(path_parts[4])
            except ValueError as e:
                raise ValueError("Unable to convert PR number to integer") from e
            return repo_name, pr_number

        if len(path_parts) < 4 or path_parts[2] != 'pull':
            raise ValueError("The provided URL does not appear to be a GitHub PR URL")

        repo_name = '/'.join(path_parts[:2])
        try:
            pr_number = int(path_parts[3])
        except ValueError as e:
            raise ValueError("Unable to convert PR number to integer") from e

        return repo_name, pr_number

    def _get_github_client(self):
        deployment_type = settings.get("GITHUB.DEPLOYMENT_TYPE", "user")

        if deployment_type == 'app':
            try:
                private_key = settings.github.private_key
                app_id = settings.github.app_id
            except AttributeError as e:
                raise ValueError("GitHub app ID and private key are required when using GitHub app deployment") from e
            if not self.installation_id:
                raise ValueError("GitHub app installation ID is required when using GitHub app deployment")
            auth = AppAuthentication(app_id=app_id, private_key=private_key,
                                     installation_id=self.installation_id)
            return Github(app_auth=auth)

        if deployment_type == 'user':
            try:
                token = settings.github.user_token
            except AttributeError as e:
                raise ValueError("GitHub token is required when using user deployment") from e
            return Github(token)

    def _get_repo(self):
        return self.github_client.get_repo(self.repo)

    def _get_pr(self):
        return self._get_repo().get_pull(self.pr_num)

    def _get_pr_file_content(self, file: FilePatchInfo, sha: str):
        try:
            file_content_str = self._get_repo().get_contents(file.filename, ref=sha).decoded_content.decode()
        except Exception:
            file_content_str = ""
        return file_content_str