#!/usr/bin/env python3
"""sjcode client.

Terminal coding-agent front end for the sjcode daemon (server/server.py).

On start it asks which server to connect to. Servers you used before are
remembered in ~/.config/sjcode/client.json together with username and the
last model, so next time you just press Enter. New servers are saved too.

Flow:
    coder                     -> banner, pick saved server (or add one),
                                 login, pick model, chat REPL
    coder 10.0.0.5:8420       -> skip the server picker
    coder --model qwen3-coder -> skip the model picker

REPL commands:
    /help /server /model /models /limit /clear /quit
"""

from __future__ import annotations

import argparse
import getpass
import json
import os
import re
import sys
import time
import urllib.error
import urllib.parse
import urllib.request
from pathlib import Path

CONFIG_DIR = Path(os.environ.get("XDG_CONFIG_HOME", Path.home() / ".config")) / "sjcode"
CONFIG_FILE = CONFIG_DIR / "client.json"

DEFAULT_PORT = 8420
REQUEST_TIMEOUT = 300
HISTORY_TURNS = 10  # prior turns sent with each message for context

HOST_RE = re.compile(
    r"^(?=.{1,253}\z)"                     # total length limit
    r"(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)+"  # domain labels +
    r"[a-z]{2,63}\z"                       # a TLD
    r"|^[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\z"      # or single-label hostname
    r"|^(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(?:\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}\z"  # IPv4
    r"|^(?:[0-9a-f]{0,4}:){2,7}[0-9a-f]{0,4}\z",     # IPv6 (2+ colons)
    re.IGNORECASE,
)

# Makes the model behave like a terminal agent: short lines, check marks.
AGENT_PREAMBLE = (
    "You are sj, a coding agent working in the user's terminal.\n"
    "Answer concisely and practically.\n"
    "Describe what you do as short lines; put every action you performed "
    "or verified on its own line starting with '\u2713 ' (check mark).\n"
    "End your reply with the single line 'Done.'"
)


# ---------------------------------------------------------------------------
# small terminal helpers (ANSI, no dependencies)
# ---------------------------------------------------------------------------

class Style:
    def __init__(self, enabled: bool) -> None:
        self.dim = "\033[2m" if enabled else ""
        self.bold = "\033[1m" if enabled else ""
        self.green = "\033[32m" if enabled else ""
        self.yellow = "\033[33m" if enabled else ""
        self.red = "\033[31m" if enabled else ""
        self.cyan = "\033[36m" if enabled else ""
        self.reset = "\033[0m" if enabled else ""


def style_enabled() -> bool:
    if os.environ.get("NO_COLOR"):
        return False
    return sys.stdout.isatty()


ST = Style(style_enabled())


def ask(prompt: str) -> str:
    """input() that exits cleanly on Ctrl+D instead of crashing."""
    try:
        return input(prompt)
    except EOFError:
        print()
        sys.exit(1)


def banner(model: str, project: str, server: str) -> None:
    title = "sj Coding Agent"
    lines = [f"Model: {model}", f"Project: {project}"]
    width = max(len(title), *(len(l) for l in lines)) + 2
    print(f"\u256d{'\u2500' * (width + 2)}\u256e")
    print(f"\u2502 {title.center(width)} \u2502")
    for line in lines:
        print(f"\u2502 {line.ljust(width)} \u2502")
    print(f"\u2570{'\u2500' * (width + 2)}\u256f")
    print(f"{ST.dim}server: {server}  (\u2018/help\u2019 for commands){ST.reset}")


def shorten_home(path: Path) -> str:
    home = Path.home()
    try:
        return "~" / path.relative_to(home)
    except ValueError:
        return path


# ---------------------------------------------------------------------------
# saved servers
# ---------------------------------------------------------------------------

def load_state() -> dict:
    try:
        with open(CONFIG_FILE, encoding="utf-8") as fh:
            data = json.load(fh)
        if isinstance(data, dict) and isinstance(data.get("servers"), list):
            return data
    except (OSError, json.JSONDecodeError):
        pass
    return {"servers": [], "last": ""}


def save_state(state: dict) -> None:
    CONFIG_DIR.mkdir(parents=True, exist_ok=True)
    with open(CONFIG_FILE, "w", encoding="utf-8") as fh:
        json.dump(state, fh, indent=2)


def server_label(entry: dict) -> str:
    return f"{entry['host']}:{entry['port']}"


def find_server(state: dict, host: str, port: int) -> dict | None:
    for entry in state["servers"]:
        if entry["host"] == host and int(entry["port"]) == port:
            return entry
    return None


def parse_address(text: str) -> tuple[str, int]:
    """Accept 'domain', 'ip', 'host:port', IPv6 or a full http(s) URL."""
    text = text.strip()
    if "://" in text:
        parsed = urllib.parse.urlsplit(text)
        host, port = parsed.hostname or "", parsed.port or DEFAULT_PORT
    elif text.startswith("["):  # [ipv6]:port
        parsed = urllib.parse.urlsplit("//" + text)
        host, port = parsed.hostname or "", parsed.port or DEFAULT_PORT
    elif text.count(":") > 1:  # bare IPv6 literal (no port part)
        host, port = text, DEFAULT_PORT
    else:
        host, _, port_s = text.rpartition(":")
        if not host or not port_s.isdigit() or not (0 < int(port_s) < 65536):
            host, port = text, DEFAULT_PORT
        else:
            port = int(port_s)
    host = host.strip("[]").strip().lower()
    if not host or not HOST_RE.match(host):
        raise ValueError(f"not a valid host: {text!r}")
    return host, port


def pick_server(state: dict) -> tuple[dict, bool]:
    """Ask which server to use. Returns (entry, created_new)."""
    servers = state["servers"]
    print(f"\n{ST.bold}Connect to which server?{ST.reset}")
    for i, entry in enumerate(servers, 1):
        default = "  (last)" if server_label(entry) == state.get("last") else ""
        user = f"  as {entry['username']}" if entry.get("username") else ""
        print(f"  {i}) {server_label(entry)}{user}{default}")
    print(f"  n) add a new server\n")

    hint = ""
    if servers:
        idx = next(
            (i for i, e in enumerate(servers, 1) if server_label(e) == state.get("last")),
            1,
        )
        hint = str(idx)

    while True:
        choice = ask(f"server [1-{len(servers)}/n{', Enter=' + hint if hint else ''}]: ").strip().lower()
        if not choice and hint:
            entry = servers[int(hint) - 1]
            return entry, False
        if choice == "n":
            entry = add_server(state)
            return entry, True
        if choice.isdigit() and 1 <= int(choice) <= len(servers):
            return servers[int(choice) - 1], False
        print(f"{ST.red}please enter 1-{len(servers)}, 'n', or Enter{ST.reset}")


def add_server(state: dict) -> dict:
    """Ask for a new server address, probe it and save it."""
    while True:
        raw = ask("server address (domain or ip:port): ").strip()
        try:
            host, port = parse_address(raw)
        except ValueError as exc:
            print(f"{ST.red}{exc} - use e.g. 192.168.1.10:8420 or code.my.lan{ST.reset}")
            continue
        entry = find_server(state, host, port)
        if entry is None:
            entry = {"host": host, "port": port, "username": "", "model": ""}
            state["servers"].append(entry)
        break
    return entry


# ---------------------------------------------------------------------------
# daemon API
# ---------------------------------------------------------------------------

def http_json(method: str, base: str, path: str, payload: dict | None = None,
              timeout: int = REQUEST_TIMEOUT) -> tuple[int, dict]:
    url = base + path
    data = None if payload is None else json.dumps(payload).encode()
    req = urllib.request.Request(
        url, data=data, method=method,
        headers={"Content-Type": "application/json"},
    )
    try:
        with urllib.request.urlopen(req, timeout=timeout) as resp:
            return resp.status, json.loads(resp.read().decode())
    except urllib.error.HTTPError as exc:
        try:
            return exc.code, json.loads(exc.read().decode())
        except Exception:
            return exc.code, {"error": f"HTTP {exc.code}"}
    except (urllib.error.URLError, TimeoutError, ConnectionError, OSError) as exc:
        return 0, {"error": f"cannot reach server: {exc}"}


def probe_server(entry: dict, probe: bool = True) -> str | None:
    """Return an error string, or None if the daemon answers.

    With probe=False, skip the check (e.g. HTTP proxies that intercept
    the port make a probe useless; login will fail with a clear error).
    """
    if not probe:
        return None
    base = f"http://{entry['host']}:{entry['port']}"
    status, body = http_json("GET", base, "/status", timeout=5)
    if status != 200:
        return str(body.get("error", f"no answer from {server_label(entry)}"))
    return None


def api_login(entry: dict, username: str, password: str) -> tuple[int, dict]:
    base = f"http://{entry['host']}:{entry['port']}"
    return http_json("POST", base, "/login",
                     {"username": username, "password": password}, timeout=15)


def api_models(entry: dict, token: str) -> list[str]:
    base = f"http://{entry['host']}:{entry['port']}"
    status, body = http_json(
        "GET", base, f"/models?token={urllib.parse.quote(token)}", timeout=15)
    return list(body.get("models", [])) if status == 200 else []


def api_chat(entry: dict, token: str, message: str, model: str) -> tuple[int, dict]:
    base = f"http://{entry['host']}:{entry['port']}"
    return http_json("POST", base, "/chat",
                     {"token": token, "message": message, "model": model})


# ---------------------------------------------------------------------------
# login / model selection
# ---------------------------------------------------------------------------

def login(entry: dict) -> str | None:
    """Ask credentials, return the session token (or None)."""
    default = entry.get("username") or ""
    while True:
        username = ask(f"username [{default}]: ").strip() or default
        if not username:
            print(f"{ST.red}username required{ST.reset}")
            continue
        if sys.stdin.isatty():
            try:
                password = getpass.getpass("password: ")
            except EOFError:
                print()
                sys.exit(1)
        else:  # piped stdin (scripted runs): plain input
            password = ask("password: ")
        status, body = api_login(entry, username, password)
        if status == 200:
            entry["username"] = username
            left = body.get("remaining_minutes")
            time_left = "unlimited" if left is None else f"{left:g} min left today"
            print(f"{ST.green}logged in as {username}{ST.reset} "
                  f"{ST.dim}({time_left}){ST.reset}\n")
            return str(body["token"])
        print(f"{ST.red}login failed: {body.get('error', 'unknown')}{ST.reset}")
        if status == 403:  # daily limit reached - no point retrying
            return None


def pick_model(entry: dict, models: list[str]) -> str:
    """Ask which model to use; preselects the saved one."""
    if not models:
        print(f"{ST.yellow}server lists no models, using daemon default{ST.reset}")
        return ""
    if len(models) == 1:
        return models[0]

    saved = entry.get("model") or ""
    print(f"{ST.bold}Models on {server_label(entry)}:{ST.reset}")
    for i, name in enumerate(models, 1):
        mark = f"  {ST.dim}(last used){ST.reset}" if name == saved else ""
        print(f"  {i}) {name}{mark}")
    print()

    while True:
        choice = ask(f"model [1-{len(models)}, Enter="
                     f"{models.index(saved) + 1 if saved in models else 1}]: ").strip()
        if not choice:
            return saved if saved in models else models[0]
        if choice in models:
            return choice
        if choice.isdigit() and 1 <= int(choice) <= len(models):
            return models[int(choice) - 1]
        print(f"{ST.red}pick 1-{len(models)} or a model name{ST.reset}")


# ---------------------------------------------------------------------------
# the agent look
# ---------------------------------------------------------------------------

def print_agent_reply(text: str) -> None:
    print(f"{ST.bold}Agent:{ST.reset}")
    for line in text.rstrip().splitlines():
        stripped = line.strip()
        if stripped.startswith("\u2713"):
            print(f"  {ST.green}\u2713{ST.reset} {stripped.lstrip('\u2713').strip()}")
        elif stripped.lower() == "done.":
            print(f"  {ST.bold}{stripped}{ST.reset}")
        else:
            print(f"  {line.strip() if stripped else ''}")


def build_prompt(history: list[tuple[str, str]], message: str) -> str:
    """Plain-text transcript + new user message (server endpoint is stateless)."""
    parts = [AGENT_PREAMBLE]
    for user_text, answer in history[-HISTORY_TURNS:]:
        parts.append(f"User: {user_text}\nAssistant: {answer}")
    parts.append(f"User: {message}\nAssistant:")
    return "\n\n".join(parts)


# ---------------------------------------------------------------------------
# chat REPL
# ---------------------------------------------------------------------------

HELP = """
commands:
  /help            show this help
  /server          show the connected server
  /models          list models on the server
  /model <name>    switch model (also saved for this server)
  /limit           show remaining minutes today (last known)
  /clear           forget the conversation history
  /quit            exit (also Ctrl+D)
anything else is sent to the model.
"""


def chat_loop(entry: dict, token: str, model: str, remaining: float | None) -> None:
    history: list[tuple[str, str]] = []
    while True:
        try:
            message = input(f"{ST.cyan}you>{ST.reset} ").strip()
        except EOFError:
            print()
            return
        except KeyboardInterrupt:
            print()
            continue
        if not message:
            continue

        if message.startswith("/"):
            cmd, _, arg = message.partition(" ")
            if cmd in ("/quit", "/exit", "/q"):
                return
            if cmd == "/help":
                print(HELP.strip())
            elif cmd == "/server":
                print(f"connected to {server_label(entry)} as {entry.get('username')}")
            elif cmd == "/models":
                models = api_models(entry, token)
                print("\n".join(models) or f"{ST.red}no models listed{ST.reset}")
            elif cmd == "/model":
                if arg.strip():
                    model = arg.strip()
                    entry["model"] = model
                    print(f"model set to {model}")
                else:
                    print(f"current model: {model or '(daemon default)'}")
            elif cmd == "/limit":
                left = "unlimited" if remaining is None else f"{remaining:g} min"
                print(f"time left today: {left}")
            elif cmd == "/clear":
                history.clear()
                print("history cleared")
            else:
                print(f"unknown command {cmd} - try /help")
            continue

        try:
            status, body = api_chat(entry, token, build_prompt(history, message), model)
        except KeyboardInterrupt:
            print(f"\n{ST.yellow}request cancelled{ST.reset}")
            continue

        if status != 200:
            print(f"{ST.red}error: {body.get('error', 'unknown')}{ST.reset}")
            if status == 403:
                return  # daily limit reached
            continue

        answer = str(body.get("response", "")).strip() or "(empty reply)"
        history.append((message, answer))
        print()
        print_agent_reply(answer)
        remaining = body.get("remaining_minutes")
        if remaining is not None:
            print(f"{ST.dim}  ({remaining:g} min left today){ST.reset}")
        print()


# ---------------------------------------------------------------------------
# main
# ---------------------------------------------------------------------------

def main() -> None:
    if os.name == "nt":
        os.system("")  # enable ANSI escapes in classic Windows consoles

    parser = argparse.ArgumentParser(description="sj coding agent client")
    parser.add_argument("server", nargs="?",
                        help="server address (domain or ip:port), skips the picker")
    parser.add_argument("-m", "--model", help="model to use, skips the picker")
    parser.add_argument("--no-probe", action="store_true",
                        help="skip the reachability check before login (use behind "
                             "HTTP proxies that answer for every port)")
    args = parser.parse_args()

    state = load_state()

    # -- choose server ------------------------------------------------------
    if args.server:
        try:
            host, port = parse_address(args.server)
        except ValueError:
            sys.exit(f"error: cannot parse address '{args.server}'")
        entry = find_server(state, host, port)
        created = entry is None
        if entry is None:
            entry = {"host": host, "port": port, "username": "", "model": ""}
            state["servers"].append(entry)
    else:
        if not state["servers"]:
            print(f"{ST.bold}First start - let's add a server.{ST.reset}")
            entry = add_server(state)
            created = True
        else:
            entry, created = pick_server(state)

    label = server_label(entry)
    if created:
        save_state(state)  # persist immediately, before anything can go wrong

    print(f"\nconnecting to {label} ...")
    if (err := probe_server(entry, probe=not args.no_probe)) is not None:
        print(f"{ST.red}error: {err}{ST.reset}")
        if created:
            print(f"{ST.dim}'{label}' was saved - start coder again once it is reachable{ST.reset}")
        else:
            print(f"{ST.dim}saved under '{label}' - try again later{ST.reset}")
        sys.exit(1)

    # -- login ----------------------------------------------------------------
    token = login(entry)
    if token is None:
        save_state(state)
        sys.exit(1)

    # -- choose model ---------------------------------------------------------
    models = api_models(entry, token)
    model = args.model or pick_model(entry, models)

    if model:
        entry["model"] = model
    state["last"] = label
    save_state(state)

    project = shorten_home(Path.cwd())
    banner(model or "(server default)", str(project), label)
    chat_loop(entry, token, model, None)
    print("bye")


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        print("\nbye")