from __future__ import annotations

import dataclasses
import datetime
import re


@dataclasses.dataclass
class BackfillParams:
    dag_name: str
    start_date: str
    end_date: str
    clear: bool
    dry_run: bool
    task_regex: str | None

    def validate_date_range(self) -> None:
        start_date = datetime.datetime.fromisoformat(self.start_date)
        end_date = datetime.datetime.fromisoformat(self.end_date)
        if start_date > end_date:
            raise ValueError(
                f"`start_date`={self.start_date} is greater than `end_date`={self.end_date}"
            )

    def validate_regex_pattern(self) -> None:
        if self.task_regex:
            try:
                re.compile(self.task_regex)
            except re.error:
                raise ValueError(
                    f"Invalid regex pattern for `task_regex`={self.task_regex}"
                ) from None

    def generate_backfill_command(self) -> list[str]:
        """
        Backfill command based off the Airflow plugin implemented by hwoo.

        Original implementation in plugins/backfill/main.py

        """
        # Construct the airflow command
        cmd = ["airflow"]

        if self.clear:
            cmd.extend(["tasks", "clear"])

            if self.dry_run:
                # For dry runs we simply time out to avoid zombie procs waiting on user input.
                # The output is what we're interested in
                timeout_list = ["timeout", "60"]
                cmd = timeout_list + cmd
            else:
                cmd.append("-y")

            if self.task_regex:
                cmd.extend(["-t", str(self.task_regex)])
        else:
            cmd.extend(["dags", "backfill", "--donot-pickle"])
            if self.dry_run:
                cmd.append("--dry-run")

            if self.task_regex:
                cmd.extend(["-t", str(self.task_regex)])

        cmd.extend(
            ["-s", str(self.start_date), "-e", str(self.end_date), str(self.dag_name)]
        )

        return cmd