#!/usr/bin/env python3

import json
import os
import sys

# Get relative imports to work when the package is not installed on the PYTHONPATH.
if __name__ == "__main__" and __package__ is None:
    sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from buildscripts.ciconfig.evergreen import parse_evergreen_file
from buildscripts.resmokelib.utils import evergreen_conn

FILE_SIZE_THRESHOLD_IN_BYTES = 16 * 1024 * 1024  # 16MB
FALLBACK_TASK_COUNT_THRESHOLD = 50_000  # if we can't reach Evergreen API for any reason

# buffer to avoid hitting the limit exactly and leave room for
# tasks generated by tasks other than version_gen
TASK_BUFFER = 1500


def validate_file_size(file_path: str) -> None:
    """Validate that the generated tasks config file size is below the threshold. This only fails if the file is missing. A warning is issued if the file size exceeds the threshold."""

    file_path = os.path.join(os.path.dirname(os.getcwd()), file_path)
    if not os.path.exists(file_path):
        raise FileNotFoundError(f"{file_path} does not exist")

    file_size_in_bytes = os.path.getsize(file_path)
    if file_size_in_bytes > FILE_SIZE_THRESHOLD_IN_BYTES:
        print(
            f"WARNING! {file_path} is {file_size_in_bytes} bytes, exceeding threshold "
            f"{FILE_SIZE_THRESHOLD_IN_BYTES} bytes. File upload may fail due to network issues, or Evergreen "
            f"may reject very large yaml sizes"
        )
    else:
        print(
            f"File size validation passed: {file_path} is {file_size_in_bytes} bytes (threshold: {FILE_SIZE_THRESHOLD_IN_BYTES})"
        )


def get_task_limit_from_evergreen() -> int:
    """Fetch the task limit from Evergreen's REST API."""
    try:
        # Call the admin/task_limits endpoint
        evg_api = evergreen_conn.get_evergreen_api()
        url = evg_api._create_url("/admin/task_limits")
        json = evg_api._call_api(url, method="GET").json()
        task_limit = json.get("max_tasks_per_version")

        if task_limit is None:
            print(
                f"WARNING: 'max_tasks_per_version' not found in API response, using fallback: {FALLBACK_TASK_COUNT_THRESHOLD}"
            )
            return FALLBACK_TASK_COUNT_THRESHOLD

        print(f"Fetched task limit from Evergreen API: {task_limit}")
        return task_limit
    except Exception as e:
        print(
            f"WARNING: Failed to fetch task limit from Evergreen API ({e}), using fallback: {FALLBACK_TASK_COUNT_THRESHOLD}"
        )
        return FALLBACK_TASK_COUNT_THRESHOLD


def calculate_total_task_count(config: dict) -> int:
    task_group_dict = {tg["name"]: len(tg["tasks"]) for tg in config.get("task_groups", [])}

    task_count = 0
    for bv in config.get("buildvariants", []):
        for t in bv.get("tasks", []):
            if t["name"] in task_group_dict:  # expand task group
                task_count += task_group_dict[t["name"]]
            else:
                task_count += 1

    display_tasks = sum(len(bv.get("display_tasks", [])) for bv in config.get("buildvariants", []))
    task_count += display_tasks

    return task_count


def calculate_generated_task_count() -> int:
    """Calculate the total number of generated tasks from the Evergreen config file."""

    # Script runs from src/ directory, so generated config is at ./generated_resmoke_config/evergreen_config.json
    config_path = os.path.join(os.getcwd(), "generated_resmoke_config", "evergreen_config.json")

    try:
        with open(config_path, "r") as f:
            config = json.load(f)
        return calculate_total_task_count(config)

    except Exception as e:
        raise Exception(f"Failed to calculate generated task count: {e}")


def calculate_nongenerated_task_count() -> int:
    """Calculate the total number of non-generated tasks from the Evergreen config file."""

    evg_project_conf = parse_evergreen_file("etc/evergreen.yml")
    config = evg_project_conf._conf

    return calculate_total_task_count(config)


def validate_task_count() -> None:
    """Validate that the total number of generated tasks is below the threshold."""

    generated_task_num = calculate_generated_task_count()
    print(f"Generated task count: {generated_task_num}")

    nongenerated_task_num = calculate_nongenerated_task_count()
    print(f"Non-generated task count: {nongenerated_task_num}")

    total_tasks = generated_task_num + nongenerated_task_num
    print(f"Total task count: {total_tasks}")

    total_tasks = total_tasks + TASK_BUFFER
    print(f"Total task count with buffer ({TASK_BUFFER}): {total_tasks}")

    task_limit = get_task_limit_from_evergreen()

    if total_tasks > task_limit:
        raise Exception(
            f"Generated configuration contains {total_tasks} tasks, exceeding threshold "
            f"of {task_limit} tasks. This causes Evergreen performance issues or failures. Reduce the number of tasks."
        )

    print(f"Task count validation passed: {total_tasks} tasks (threshold: {task_limit})")


def main():
    args = sys.argv[1:]
    tgz_file = args[0]  # tgz file

    validate_file_size(tgz_file)

    validate_task_count()


if __name__ == "__main__":
    main()