import json
import re
import shlex
import shutil
import subprocess
import sys


# Mixed into DevCommand (bin/dev), which provides PROJECT_NAME, _project_root
# and _exec_in_root.
class GiteaCommand:
    ##
    # Checks out a branch named after a Gitea issue URL.
    # If the issue is from this project's repo, the branch name will be:
    #   issue-<issue_number>/<issue_title>
    # If the issue is from another repo (presumably upstream), the branch name will be:
    #   <issue_owner>-issue-<issue_number>/<issue_title>
    def branch_from(self, *args, **kwargs):
        issue_url = args[0] if args else None
        if issue_url is None:
            raise ValueError("Must provide a Gitea issue URL.")

        base_url, issue_repo, issue_number = self._parse_issue_url(issue_url)
        issue_title = self._fetch_issue_title(base_url, issue_repo, issue_number)
        branch_name = self._format_branch_name(issue_repo, issue_number, issue_title)

        exists = subprocess.run(
            ["git", "-C", self._project_root(), "rev-parse", "--verify", "--quiet", f"refs/heads/{branch_name}"],
            stdout=subprocess.DEVNULL,
        ).returncode == 0
        flag = "" if exists else "-b "
        self._exec_in_root(f"git checkout {flag}{shlex.quote(branch_name)}", replace=True)

    ##
    # Creates an issue on this project's Gitea repo.
    #   dev issue <title> [-b|--body <text>] [-l|--label <name>]... [-a|--assignee <user>]... [-o|--open]
    # The body is read from stdin if --body is not given and stdin is piped.
    # Gitea's API cannot add issues to a project (only the web UI can), so the
    # issue URL is printed and --open opens it in the browser to do so.
    def issue(self, *args, **kwargs):
        title, body, labels, assignees, open_in_browser = self._parse_issue_args(args)

        repo = self._origin_repo()
        if repo is None:
            raise RuntimeError("could not determine the Gitea repo from the origin remote")

        payload = {"title": title, "body": body}
        if labels:
            label_ids = self._fetch_label_ids(repo)
            unknown = [label for label in labels if label not in label_ids]
            if unknown:
                raise ValueError(f"Unknown label(s): {', '.join(unknown)} (available: {', '.join(sorted(label_ids))})")
            payload["labels"] = [label_ids[label] for label in labels]
        if assignees:
            payload["assignees"] = assignees

        issue = self._tea_api(f"repos/{repo}/issues", payload)
        print(f"Created issue #{issue['number']}: {issue['title']}")
        print(issue["html_url"])
        print(f"Add it to the project from the issue sidebar: Projects > {self.PROJECT_NAME}")

        if open_in_browser:
            opener = shutil.which("xdg-open") or shutil.which("open")
            if opener is None:
                raise RuntimeError("xdg-open not found on PATH")
            subprocess.Popen([opener, issue["html_url"]], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)

    def _parse_issue_url(self, url):
        match = re.match(r"^(https?://[^/]+)/([^/]+)/([^/]+)/issues/(\d+)", url)
        if match is None:
            raise ValueError(f"Not a Gitea issue URL: {url}")
        return match[1], f"{match[2]}/{match[3]}", match[4]

    def _fetch_issue_title(self, base_url, repo, issue_number):
        if shutil.which("tea") is None:
            raise RuntimeError("tea not found on PATH (install gitea tea and run `tea login add`)")

        endpoint = f"{base_url}/api/v1/repos/{repo}/issues/{issue_number}"
        print(f"Running: tea api {endpoint}")
        result = subprocess.run(["tea", "api", endpoint], stdout=subprocess.PIPE, text=True)
        if result.returncode != 0:
            raise RuntimeError(f"failed to fetch issue title from {endpoint}")
        return json.loads(result.stdout)["title"]

    def _parse_issue_args(self, args):
        title = None
        body = None
        labels = []
        assignees = []
        open_in_browser = False

        args = list(args)
        while args:
            arg = args.pop(0)
            if arg in ("-b", "--body", "-l", "--label", "-a", "--assignee"):
                if not args:
                    raise ValueError(f"{arg} requires a value")
                value = args.pop(0)
                if arg in ("-b", "--body"):
                    body = value
                elif arg in ("-l", "--label"):
                    labels.append(value)
                else:
                    assignees.append(value)
            elif arg in ("-o", "--open"):
                open_in_browser = True
            elif arg.startswith("-"):
                raise ValueError(f"Unknown option: {arg}")
            elif title is None:
                title = arg
            else:
                title = f"{title} {arg}"

        if not title:
            raise ValueError("Must provide an issue title. Usage: dev issue <title> [-b <body>] [-l <label>]... [-a <user>]... [-o]")
        if body is None:
            body = "" if sys.stdin.isatty() else sys.stdin.read()
        return title, body, labels, assignees, open_in_browser

    def _tea_api(self, endpoint, payload=None):
        if shutil.which("tea") is None:
            raise RuntimeError("tea not found on PATH (install gitea tea and run `tea login add`)")

        command = ["tea", "api", endpoint]
        if payload is not None:
            command += ["-d", "@-"]
        print(f"Running: {' '.join(command)}")
        result = subprocess.run(
            command,
            input=json.dumps(payload) if payload is not None else None,
            stdout=subprocess.PIPE,
            text=True,
        )
        if result.returncode != 0:
            raise RuntimeError(f"tea api request failed: {endpoint}")
        return json.loads(result.stdout)

    def _fetch_label_ids(self, repo):
        labels = self._tea_api(f"repos/{repo}/labels?limit=100")
        return {label["name"]: label["id"] for label in labels}

    def _format_branch_name(self, issue_repo, issue_number, issue_title):
        formatted_title = re.sub(r"-+", "-", re.sub(r"[^a-z0-9\-]", "", re.sub(r"\s+", "-", issue_title.lower().strip())))
        if issue_repo == self._origin_repo():
            return f"issue-{issue_number}/{formatted_title}"
        issue_owner = issue_repo.split("/")[0]
        return f"{issue_owner}-issue-{issue_number}/{formatted_title}"

    def _origin_repo(self):
        result = subprocess.run(
            ["git", "-C", self._project_root(), "remote", "get-url", "origin"],
            stdout=subprocess.PIPE,
            text=True,
        )
        match = re.search(r"[:/]([^/:]+/[^/]+?)(?:\.git)?$", result.stdout.strip())
        return match[1] if match else None