#!/usr/bin/env python3
import argparse
import json
import os
import shlex
import subprocess
import sys


def nginx_v_output(nginx_bin):
    proc = subprocess.run(
        [nginx_bin, "-V"],
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        text=True,
        check=True,
    )
    return proc.stdout


def parse_nginx_v(output):
    version = ""
    configure_line = ""

    for line in output.splitlines():
        if line.startswith("nginx version:"):
            version = line.split(":", 1)[1].strip()
        elif line.startswith("configure arguments:"):
            configure_line = line.split(":", 1)[1].strip()

    if not configure_line:
        raise RuntimeError("nginx -V did not include configure arguments")

    return version, configure_line, shlex.split(configure_line)


def option_value(args, option):
    prefix = option + "="
    for arg in args:
        if arg.startswith(prefix):
            return arg[len(prefix) :]
    return ""


def rewrite_module_path(arg, nginx_src):
    for option in ("--add-module=", "--add-dynamic-module="):
        if not arg.startswith(option):
            continue

        module_path = arg[len(option) :]
        if os.path.exists(module_path):
            return arg

        marker = "/debian/modules/"
        if marker in module_path:
            suffix = module_path.split(marker, 1)[1]
            candidate = os.path.join(nginx_src, "debian", "modules", suffix)
            if os.path.exists(candidate):
                return option + candidate

        marker = "/debian/"
        if marker in module_path:
            suffix = module_path.split(marker, 1)[1]
            candidate = os.path.join(nginx_src, "debian", suffix)
            if os.path.exists(candidate):
                return option + candidate

    return arg


def add_extra_cc_opt(args, extra_cc_opt):
    if not extra_cc_opt:
        return args

    rewritten = []
    found = False

    for arg in args:
        if arg.startswith("--with-cc-opt="):
            found = True
            rewritten.append(arg + " " + extra_cc_opt)
        else:
            rewritten.append(arg)

    if not found:
        rewritten.append("--with-cc-opt=" + extra_cc_opt)

    return rewritten


def rewrite_configure_args(args, nginx_src, extra_cc_opt):
    if not nginx_src:
        return add_extra_cc_opt(args, extra_cc_opt)

    rewritten = [rewrite_module_path(arg, nginx_src) for arg in args]
    return add_extra_cc_opt(rewritten, extra_cc_opt)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--nginx-bin", default="nginx")
    parser.add_argument("--nginx-src", default="")
    parser.add_argument("--extra-cc-opt", default="")
    parser.add_argument("--json", action="store_true")
    parser.add_argument("--configure-line", action="store_true")
    parser.add_argument("--modules-path", action="store_true")
    args = parser.parse_args()

    output = nginx_v_output(args.nginx_bin)
    version, configure_line, configure_args = parse_nginx_v(output)
    rewritten_args = rewrite_configure_args(
        configure_args,
        args.nginx_src,
        args.extra_cc_opt,
    )

    modules_path = option_value(configure_args, "--modules-path")
    if not modules_path:
        prefix = option_value(configure_args, "--prefix") or "/usr/share/nginx"
        modules_path = os.path.join(prefix, "modules")

    if args.configure_line:
        print(shlex.join(rewritten_args))
        return

    if args.modules_path:
        print(modules_path)
        return

    if args.json:
        json.dump(
            {
                "version": version,
                "configure_line": configure_line,
                "configure_args": configure_args,
                "rewritten_configure_args": rewritten_args,
                "modules_path": modules_path,
            },
            sys.stdout,
            indent=2,
            sort_keys=True,
        )
        sys.stdout.write("\n")
        return

    parser.error("choose one of --json, --configure-line, or --modules-path")


if __name__ == "__main__":
    main()