#!/usr/bin/env python3

import argparse

import fnmatch

from pathlib import Path

import yaml

ROOT = Path(__file__).resolve().parents[1]

def load_inventory(path: Path) -> dict:

    with path.open("r", encoding="utf-8") as handle:

        data = yaml.safe_load(handle)

    if data.get("version") != 1:

        raise SystemExit("unsupported inventory version")

    return data

def fmt_bool(value: bool) -> str:

    return "yes" if value else "no"

def fmt_option(value) -> str:

    if isinstance(value, bool):

        return fmt_bool(value)

    return str(value)

def aliases_match_rule(aliases, rule):

    patterns = rule.get("patterns", [])

    if not patterns:

        return False

    return all(any(fnmatch.fnmatch(str(alias), pattern) for pattern in patterns) for alias in aliases)

def company_managed_rule(data, target, aliases, user, port):

    managed = data.get("company_managed", {}).get("jump_hosts", {})

    if target not in managed.get("inherit_globals_on_targets", []):

        return None

    for rule in managed.get("match_defaults", []):

        if rule.get("user") != user or rule.get("port") != port:

            continue

        if aliases_match_rule(aliases, rule):

            return rule

    return None

def aliases_for_host(host):

    aliases = [str(alias) for alias in host["aliases"]]

    if host["hostname"] not in aliases:

        aliases.append(host["hostname"])

    return aliases

def host_block(aliases, hostname, user=None, port=None, extra=None):

    lines = [f"Host {' '.join(str(alias) for alias in aliases)}", f"    HostName {hostname}"]

    if user:

        lines.append(f"    User {user}")

    if port:

        lines.append(f"    Port {port}")

    auth = (extra or {}).pop("auth", None)

    if auth == "password_interactive":

        lines.append("    SetEnv NG_SSH_AUTH=password-interactive")

        lines.append("    BatchMode no")

        lines.append("    PreferredAuthentications keyboard-interactive,password")

        lines.append("    PubkeyAuthentication no")

    for key, value in (extra or {}).items():

        lines.append(f"    {key} {value}")

    lines.append("")

    return lines

def pattern_block(pattern, options):

    lines = [f"Host {pattern}"]

    if "connect_timeout" in options:

        lines.append(f"    ConnectTimeout {options['connect_timeout']}")

    if "connection_attempts" in options:

        lines.append(f"    ConnectionAttempts {options['connection_attempts']}")

    lines.append("")

    return lines

def generated_header(target, include_comments=True):

    if not include_comments:

        return []

    return [

        "# Generated by tools/generate-configs.py.",

        "# Do not edit this file directly; edit inventory/hosts.yaml.",

        f"# Target: {target}",

        "",

    ]

def emit_global_options(data, include_comments=True):

    blocks = data.get("ssh_options", {})

    if not blocks:

        return []

    lines = []

    if include_comments:

        lines.extend(["# Global SSH compatibility options", ""])

    for name, block in blocks.items():

        if include_comments:

            lines.append(f"# {name}: {block.get('description', '')}")

        lines.append("Host *")

        for key, value in block.get("options", {}).items():

            lines.append(f"    {key} {fmt_option(value)}")

        lines.append("")

    return lines

def inherit_globals(data, target):

    managed = data.get("company_managed", {}).get("jump_hosts", {})

    return target in managed.get("inherit_globals_on_targets", [])

def merged(defaults, group_defaults, host):

    result = dict(defaults)

    result.update(group_defaults or {})

    result.update(host)

    return result

def host_differs_from_defaults(host, defaults):

    for key in ("user", "port", "auth"):

        if key in host and host[key] != defaults.get(key):

            return True

    return False

def should_emit_host_on_target(data, target, group_defaults, host):

    if target not in ("j1", "j2"):

        return True

    baseline = merged(data["defaults"]["final_host"], group_defaults, {})

    return host_differs_from_defaults(host, baseline)

def emit_entrypoints(data, include_comments=True):

    lines = ["# Entrypoints", ""] if include_comments else []

    for host in data["entrypoints"].values():

        extra = {}

        if host.get("identity_file"):

            extra["IdentityFile"] = host["identity_file"]

        if "identities_only" in host:

            extra["IdentitiesOnly"] = fmt_bool(host["identities_only"])

        lines.extend(host_block(aliases_for_host(host), host["hostname"], host.get("user"), host.get("port"), extra))

    return lines

def emit_jumps(data, include_comments=True):

    lines = ["# Jump hosts", ""] if include_comments else []

    defaults = data["defaults"]["jump"]

    for jump in data["jumps"].values():

        item = merged(defaults, {}, jump)

        lines.extend(host_block(aliases_for_host(item), item["hostname"], item.get("user"), item.get("port")))

    return lines

def emit_hosts_for_group(data, group, target, defaults):

    group_defaults = group.get("defaults", {})

    lines = []

    for host in group.get("hosts", {}).values():

        if not should_emit_host_on_target(data, target, group_defaults, host):

            continue

        item = merged(defaults, group_defaults, host)

        aliases = aliases_for_host(item)

        extra = {}

        if item.get("auth"):

            extra["auth"] = item["auth"]

        user = item.get("user")

        port = item.get("port")

        if company_managed_rule(data, target, aliases, user, port):

            user = None

            port = None

        lines.extend(host_block(aliases, item["hostname"], user, port, extra))

    for pattern, options in group.get("patterns", {}).items():

        lines.extend(pattern_block(pattern, options))

    return lines

def emit_groups(data, target=None, include_comments=True):

    lines = []

    defaults = data["defaults"]["final_host"]

    metadata_keys = {"description", "default_jump", "defaults", "patterns", "hosts"}

    queue = [(name, group) for name, group in data["groups"].items()]

    while queue:

        group_name, group = queue.pop(0)

        group_lines = emit_hosts_for_group(data, group, target, defaults)

        if group_lines:

            if include_comments:

                lines.extend([f"# Group: {group_name}", f"# Description: {group.get('description', '')}", ""])

            lines.extend(group_lines)

        for child_name, child in group.items():

            if child_name in metadata_keys or not isinstance(child, dict):

                continue

            if "hosts" in child:

                queue.append((f"{group_name}.{child_name}", child))

    return lines

def write(path: Path, lines):

    path.parent.mkdir(parents=True, exist_ok=True)

    path.write_text("\n".join(lines).rstrip() + "\n", encoding="utf-8")

def generate(data, output_dir: Path):

    final_groups = emit_groups(data)

    client = generated_header("client")

    client.extend(emit_global_options(data))

    client.extend(emit_entrypoints(data))

    client.extend(emit_jumps(data))

    client.extend(final_groups)

    write(output_dir / "client.conf", client)

    is_jumper = generated_header("is-jumper")

    is_jumper.extend(emit_global_options(data))

    is_jumper.extend(emit_jumps(data))

    write(output_dir / "is-jumper.conf", is_jumper)

    for target in ("j1", "j2"):

        lines = generated_header(target, include_comments=False)

        if inherit_globals(data, target):

            pass

        else:

            lines.extend(emit_global_options(data, include_comments=False))

        lines.extend(emit_groups(data, target, include_comments=False))

        write(output_dir / f"{target}.conf", lines)

def main():

    parser = argparse.ArgumentParser()

    parser.add_argument("--inventory", default=ROOT / "inventory" / "hosts.yaml", type=Path)

    parser.add_argument("--output-dir", default=ROOT / "generated", type=Path)

    args = parser.parse_args()

    generate(load_inventory(args.inventory), args.output_dir)

if __name__ == "__main__":

    main()