#!/usr/bin/env python3
import os
import re
import sys

# Variables that exist only for Docker Compose orchestration and must NOT be
# injected into containers as environment variables.
SHARED_ENV_EXCLUDE = frozenset(
    [
        # Docker Compose profile selection
        "COMPOSE_PROFILES",
        # Worker health check orchestration flags (consumed by docker-compose,
        # not by the application running inside the container)
        "COMPOSE_WORKER_HEALTHCHECK_DISABLED",
        "COMPOSE_WORKER_HEALTHCHECK_INTERVAL",
        "COMPOSE_WORKER_HEALTHCHECK_TIMEOUT",
    ]
)


def parse_env_example(file_path):
    """
    Parses the .env.example file and returns a dictionary with variable names as keys and default values as values.
    """
    env_vars = {}
    with open(file_path, "r", encoding="utf-8") as f:
        for line_number, line in enumerate(f, 1):
            line = line.strip()
            # Ignore empty lines and comments
            if not line or line.startswith("#"):
                continue
            # Use regex to parse KEY=VALUE
            match = re.match(r"^([^=]+)=(.*)$", line)
            if match:
                key = match.group(1).strip()
                value = match.group(2).strip()
                # Remove possible quotes around the value
                if (value.startswith('"') and value.endswith('"')) or (
                    value.startswith("'") and value.endswith("'")
                ):
                    value = value[1:-1]
                env_vars[key] = value
            else:
                print(f"Warning: Unable to parse line {line_number}: {line}")
    return env_vars


def generate_shared_env_block(env_vars, anchor_name="shared-api-worker-env"):
    """
    Generates a shared environment variables block as a YAML string.
    """
    lines = [f"x-shared-env: &{anchor_name}"]
    for key, default in env_vars.items():
        if key in SHARED_ENV_EXCLUDE:
            continue
        # If default value is empty, use ${KEY:-}
        if default == "":
            lines.append(f"  {key}: ${{{key}:-}}")
        else:
            # If default value contains special characters, wrap it in quotes
            if re.search(r"[:\s]", default):
                default = f"{default}"
            lines.append(f"  {key}: ${{{key}:-{default}}}")
    return "\n".join(lines)


def create_env_files_from_example(env_example_path):
    """
    Creates actual env files from .env.example by copying the categorized .env.example files.
    This allows docker-compose to use env_file references.
    Supports per-module structure with subdirectories.
    """
    base_dir = os.path.dirname(os.path.abspath(env_example_path))
    root_env_file = os.path.join(base_dir, ".env")
    if not os.path.exists(root_env_file):
        with open(env_example_path, "r", encoding="utf-8") as src, open(
            root_env_file, "w", encoding="utf-8", newline="\n"
        ) as dst:
            dst.write(src.read())
        print(f"Created {root_env_file}")
    else:
        print(f"{root_env_file} already exists, skipping")

    envs_dir = os.path.join(base_dir, "envs")
    if not os.path.isdir(envs_dir):
        print(f"No envs directory found at {envs_dir}, skipping split env files")
        return []

    created_files = []
    # Walk through all .env.example files in subdirectories
    for root, dirs, files in os.walk(envs_dir):
        for file in files:
            if file.endswith('.env.example'):
                example_file = os.path.join(root, file)
                env_file = example_file.replace('.env.example', '.env')

                if os.path.exists(env_file):
                    print(f"{env_file} already exists, skipping")
                    continue

                # Copy .example to actual file
                with open(example_file, "r", encoding="utf-8") as src, open(
                    env_file, "w", encoding="utf-8", newline="\n"
                ) as dst:
                    dst.write(src.read())
                created_files.append(env_file)
                print(f"Created {env_file}")
    
    return created_files


def insert_shared_env(template_path, output_path, header_comments):
    """
    Copies the template file to output path with header comments.
    The template now uses env_file references instead of a huge YAML anchor.
    """
    with open(template_path, "r", encoding="utf-8") as f:
        template_content = f.read()

    # Prepare the final content with header comments
    final_content = f"{header_comments}\n{template_content}"

    with open(output_path, "w", encoding="utf-8", newline="\n") as f:
        f.write(final_content)
    print(f"Generated {output_path}")


def main():
    base_dir = os.path.dirname(os.path.abspath(__file__))
    env_example_path = os.path.join(base_dir, ".env.example")
    template_path = os.path.join(base_dir, "docker-compose-template.yaml")
    output_path = os.path.join(base_dir, "docker-compose.yaml")

    # Define header comments to be added at the top of docker-compose.yaml
    header_comments = (
        "# ==================================================================\n"
        "# WARNING: This file is auto-generated by generate_docker_compose\n"
        "# Do not modify this file directly. Instead, update the .env.example\n"
        "# or docker-compose-template.yaml and regenerate this file.\n"
        "# ==================================================================\n"
    )

    # Check if required files exist
    for path in [env_example_path, template_path]:
        if not os.path.isfile(path):
            print(f"Error: File {path} does not exist.")
            sys.exit(1)

    # Create env files from categorized .env.example files
    # These files are used by docker-compose's env_file directive
    # This ensures .env files exist even in CI/CD environments
    create_env_files_from_example(env_example_path)

    # Copy template to output with header comments
    # The template now uses env_file references instead of a huge YAML anchor
    insert_shared_env(template_path, output_path, header_comments)


if __name__ == "__main__":
    main()