"""
openenv_loop.py — Environment interaction via OpenEnv HTTP API.

Handles:
  - env_reset / env_step HTTP calls to the AntiAtropos HF Space
  - Model-guided rollouts (generate action, step env, collect reward)
  - Heuristic baseline rollouts (for comparison)
  - Observation formatting for the LLM

Everything goes through the HTTP API — no local simulator imports needed.
"""

from __future__ import annotations

import json
import math
import re
import time
from dataclasses import dataclass, field
from enum import Enum
from typing import Any, Dict, List, Optional, Tuple

import requests
import torch

try:
    from .chat_utils import render_no_think_chat, tokenize_text_only
except ImportError:
    from chat_utils import render_no_think_chat, tokenize_text_only


# ────────────────────────────────────────────────
# Constants
# ────────────────────────────────────────────────

class ActionType(str, Enum):
    NO_OP = "NO_OP"
    SCALE_UP = "SCALE_UP"
    SCALE_DOWN = "SCALE_DOWN"
    REROUTE_TRAFFIC = "REROUTE_TRAFFIC"
    SHED_LOAD = "SHED_LOAD"


VALID_ACTIONS = [a.value for a in ActionType]
VALID_NODES = ["node-0", "node-1", "node-2", "node-3", "node-4"]
CRITICAL_NODES = {"node-0", "node-1", "node-2"}

TASK_BRIEFS = {
    "task-1": "Traffic ramps linearly every tick. Scale up proactively — new capacity takes 5 ticks to boot. Keep latency under SLA (200ms) while minimizing cost. Scale down when queues are safe.",
    "task-2": "One node (node-1 through node-4) will fail permanently. Wait until you SEE a FAILED node — do NOT pre-scale. Once a node shows status=FAILED: reroute traffic FROM the failed node to healthy peers, and scale up any starved children. Do NOT scale node-0 unless node-4 failed independently. SCALE_DOWN cancels pending boots and reduces cost. If reward is falling, stop scaling.",
    "task-3": "A surge (~75 req/tick) will hit node-1 and node-2 via a side channel bypassing node-0. Do NOT scale node-0 — it is NOT affected. ONLY scale node-1 or node-2 when their queue_depth rises. Do NOT pre-scale. 3-4 SCALE_UPs on each is sufficient. SCALE_DOWN cancels pending boots and reduces cost — use it when queues are safe. If reward is falling, STOP scaling and SCALE_DOWN to recover.",
}

SYSTEM_PROMPT = """You are an autonomous SRE controller managing a five-node microservice cluster.

CRITICAL: You are running in NO-THINK mode (/no_think). DO NOT output `</think>` or ` 
` tags. DO NOT generate reasoning blocks. DO NOT use  
 
 or . Output ONLY your action directly as plain text.

CLUSTER TOPOLOGY (traffic flows parent → children):
  node-0 → node-1, node-2
  node-2 → node-3
  node-4 (independent ingress)
FAILED nodes have outflow=0 — their children are starved.
Backpressure: overloaded children reduce parent capacity.

ACTIONS (new capacity takes 5 ticks to boot):
  SCALE_UP <node> <amount>   — add capacity (0.3-0.5 normal, 0.6-0.8 heavy surge), clears DEGRADED
  SCALE_DOWN <node> <amount>  — cancel pending boots first, then remove active capacity (0.2-0.4 safe, 0.5-0.7 aggressive)
  REROUTE_TRAFFIC <node> <fraction> — reduce THIS node capacity, redistribute to peers (0.3-0.5)
  SHED_LOAD <node> <fraction>  — drop incoming traffic (0.3-0.5), NEVER on node-0 (payment gateway)
  NO_OP                           — do nothing

REWARD PRIORITIES (in order):
  1. Avoid SLA violations (latency > 200ms or error rate > 5%)
  2. Keep queues low (growing queues = destabilizing system)
  3. Don't over-provision (excess capacity costs money)

REWARD SIGNAL: Each step returns a reward [0,1].
  > 0.5 = good. 0.15–0.5 = acceptable. < 0.15 = you are making things worse.
  If reward is falling, STOP the current strategy — try a different action or NO_OP.
  Repeating the same action when reward < 0.1 is always wrong.

Scale when your observations demand it, not preemptively.
Boot delay is 5 ticks — factor this into your timing.
Scale back down when safe to save cost.

Return exactly one JSON object:
{
  "action_type": "SCALE_UP" | "SCALE_DOWN" | "REROUTE_TRAFFIC" | "SHED_LOAD" | "NO_OP",
  "target_node_id": "node-0" | "node-1" | "node-2" | "node-3" | "node-4",
  "parameter": 0.0
}"""


# ────────────────────────────────────────────────
# HTTP Client
# ────────────────────────────────────────────────

class OpenEnvClient:
    """HTTP client for the AntiAtropos OpenEnv environment."""

    def __init__(self, env_url: str):
        self.env_url = env_url.rstrip("/")
        self._session = requests.Session()
        self._session.mount("https://", requests.adapters.HTTPAdapter(
            pool_maxsize=1, max_retries=3
        ))

    def reset(self, task_id: str = "task-1",
              seed: Optional[int] = None) -> Dict[str, Any]:
        payload: Dict[str, Any] = {"task_id": task_id}
        if seed is not None:
            payload["seed"] = seed
        resp = self._session.post(
            f"{self.env_url}/reset", json=payload, timeout=30
        )
        resp.raise_for_status()
        return resp.json()

    def step(self, action_type: str, target_node_id: str,
             parameter: float) -> Dict[str, Any]:
        payload = {
            "action": {
                "action_type": action_type,
                "target_node_id": target_node_id,
                "parameter": parameter,
            }
        }
        resp = self._session.post(
            f"{self.env_url}/step", json=payload, timeout=30
        )
        resp.raise_for_status()
        return resp.json()

    def verify(self) -> bool:
        """Smoke-test connectivity. Returns True if OK."""
        try:
            r = self.reset("task-1", seed=0)
            obs = r.get("observation", r)
            step_r = self.step("NO_OP", "node-0", 0.0)
            print(f"[openenv] Connectivity OK — "
                  f"task_id={obs.get('task_id')}, reward={step_r.get('reward')}")
            return True
        except Exception as e:
            print(f"[openenv] Connectivity FAILED: {e}")
            return False


# ────────────────────────────────────────────────
# Observation Formatting
# ────────────────────────────────────────────────

def format_observation(obs_dict: Dict, task_id: str, step: int,
                       max_steps: int, reward: float = 0.0,
                       sla_violations: int = 0) -> str:
    """Convert API observation dict to user prompt aligned with inference.py."""
    import textwrap
    brief = TASK_BRIEFS.get(task_id, "Maintain SLA, stability, and efficient cost.")

    # Synthesize cluster summary (matches inference.py build_user_prompt)
    cost_hour = obs_dict.get("current_cost_per_hour", 0.0)
    cost_dev = "low" if cost_hour < 1.2 else ("high" if cost_hour > 1.8 else "baseline")
    queue_backlog = obs_dict.get("total_queue_backlog", 0.0)
    queue_trend = "rising" if queue_backlog > 0.3 else ("stable" if queue_backlog < 0.1 else "moderate")
    sla_note = f" ({sla_violations} violations)" if sla_violations > 0 else ""
    r_tag = "GOOD" if reward > 0.5 else ("OK" if reward > 0.2 else ("BAD" if reward > 0.05 else "STOP-SCALING"))
    cluster_summary = f"Cost: {cost_dev} (${cost_hour:.2f}/hr) | Queues: {queue_trend}{sla_note} | Reward: {reward:.2f}={r_tag}"

    # Build compact observation dict (mirrors inference.py observation_for_model)
    nodes_data = []
    for n in obs_dict.get("nodes", []):
        nodes_data.append({
            "node_id": n.get("node_id"),
            "status": n.get("status", "HEALTHY"),
            "queue_depth": n.get("queue_depth", 0),
            "latency_ms": n.get("latency_ms", 0),
            "incoming_request_rate": n.get("incoming_request_rate", 0),
            "cpu_utilization": n.get("cpu_utilization", 0),
            "capacity": n.get("capacity", 0),
            "pending_capacity": n.get("pending_capacity", 0),
            "outflow_rate": n.get("outflow_rate", 0),
            "upstream_pressure": n.get("upstream_pressure", 0),
        })

    obs_compact = {
        "task_id": task_id,
        "step": step,
        "max_steps": max_steps,
        "failed_nodes": [n["node_id"] for n in obs_dict.get("nodes", []) if n.get("status") == "FAILED"],
        "degraded_nodes": [n["node_id"] for n in obs_dict.get("nodes", []) if n.get("status") == "DEGRADED"],
        "average_latency_ms": obs_dict.get("average_latency_ms", 0),
        "error_rate": obs_dict.get("error_rate", 0),
        "total_queue_backlog": obs_dict.get("total_queue_backlog", 0),
        "current_cost_per_hour": obs_dict.get("current_cost_per_hour", 0),
        "sla_violations": sla_violations,
        "nodes": nodes_data,
    }

    return textwrap.dedent(f"""
        Task: {task_id}
        Objective: {brief}
        Step: {step}
        Status: {cluster_summary}

        Current state:
        {json.dumps(obs_compact, separators=(',',':'))}

        Choose the next SRE action.
        """).strip()


# ────────────────────────────────────────────────
# Action Parsing
# ────────────────────────────────────────────────

@dataclass
class ParsedAction:
    action_type: str
    target_node_id: str
    parameter: float
    raw_text: str = ""
    is_valid: bool = True
    parse_error: str = ""


def repair_action(action_type: str, target_node_id: str, parameter: float) -> Tuple[str, str, float, str]:
    """Normalize generated JSON so the environment validator accepts it."""
    at = str(action_type).upper()
    nid = str(target_node_id or "node-0")

    if at not in VALID_ACTIONS or nid not in VALID_NODES:
        return "NO_OP", "node-0", 0.0, "invalid action schema"

    try:
        param = float(parameter)
    except (TypeError, ValueError):
        param = 0.0

    if not math.isfinite(param):
        param = 0.0

    repair_notes = []

    if at == "NO_OP":
        return at, "node-0", 0.0, ""

    if at in {"REROUTE_TRAFFIC", "SHED_LOAD"}:
        clamped = min(1.0, max(0.0, param))
        if clamped != param:
            repair_notes.append(f"clamped {at} parameter to [0,1]")
        param = clamped

    if at in {"SCALE_UP", "SCALE_DOWN"}:
        clamped = min(10.0, max(0.0, param))
        if clamped != param:
            repair_notes.append(f"clamped {at} parameter to [0,10]")
        param = clamped

    if at == "SHED_LOAD" and nid in CRITICAL_NODES:
        at = "SCALE_UP"
        param = min(0.8, max(0.3, param or 0.4))
        repair_notes.append("rewrote critical-node SHED_LOAD to SCALE_UP")

    return at, nid, round(float(param), 4), "; ".join(repair_notes)


def parse_action(text: str) -> ParsedAction:
    """Extract action from model output text."""
    try:
        start = text.find("{")
        end = text.rfind("}")
        if start == -1 or end == -1 or end < start:
            return ParsedAction("NO_OP", "node-0", 0.0, text,
                                False, "no JSON found")

        obj = json.loads(text[start:end + 1])
        at = str(obj.get("action_type", "")).upper()
        nid = str(obj.get("target_node_id", "") or "node-0")
        param = float(obj.get("parameter") or 0.0)

        if at not in VALID_ACTIONS:
            return ParsedAction("NO_OP", "node-0", 0.0, text,
                                False, f"invalid action_type: {at}")
        if nid not in VALID_NODES:
            return ParsedAction("NO_OP", "node-0", 0.0, text,
                                False, f"invalid target_node_id: {nid}")

        at, nid, param, repair_note = repair_action(at, nid, param)
        return ParsedAction(at, nid, param, text, True, repair_note)
    except Exception as e:
        return ParsedAction("NO_OP", "node-0", 0.0, text, False, str(e))


# ────────────────────────────────────────────────
# Rollout Data
# ────────────────────────────────────────────────

@dataclass
class Transition:
    """Single step in an episode rollout."""
    obs_text: str              # Formatted observation (LLM input)
    input_ids: Any             # Tokenized input IDs (tensor)
    attention_mask: Any        # Tokenized attention mask (tensor)
    action: ParsedAction       # The action taken
    reward: float              # Reward from environment
    log_prob: float = 0.0     # Log probability of action under policy


@dataclass
class Episode:
    """Complete episode rollout."""
    task_id: str
    transitions: List[Transition] = field(default_factory=list)
    total_reward: float = 0.0
    avg_reward: float = 0.0
    num_invalid: int = 0
    done: bool = False

    def finalize(self) -> None:
        if self.transitions:
            self.total_reward = sum(t.reward for t in self.transitions)
            self.avg_reward = self.total_reward / len(self.transitions)


# ────────────────────────────────────────────────
# Model-Guided Rollout
# ────────────────────────────────────────────────

def rollout_episode(
    client: OpenEnvClient,
    model,
    tokenizer,
    task_id: str,
    max_steps: int,
    cfg: Dict[str, Any],
    seed: Optional[int] = None,
) -> Episode:
    """Run one episode using the model to generate actions.

    The model generates text → we parse the JSON action → step the env →
    collect the reward. We also compute log_probs for REINFORCE.
    """
    episode = Episode(task_id=task_id)

    # Reset environment
    reset_resp = client.reset(task_id=task_id, seed=seed)
    obs_dict = reset_resp.get("observation", reset_resp)
    episode_reward = 0.0
    sla_violations = obs_dict.get("sla_violations", 0)

    # Generation config
    max_new_tokens = cfg.get("generation_max_new_tokens", 80)
    temperature = cfg.get("generation_temperature", 0.7)
    top_p = cfg.get("generation_top_p", 0.9)
    do_sample = cfg.get("generation_do_sample", True)

    for step in range(1, max_steps + 1):
        # Format observation for the LLM
        obs_text = format_observation(
            obs_dict, task_id, step, max_steps,
            episode_reward, sla_violations
        )

        # Build chat messages
        messages = [
            {"role": "system", "content": SYSTEM_PROMPT},
            {"role": "user", "content": obs_text},
        ]

        # Render via the Qwen Jinja template with thinking disabled, then
        # tokenize explicitly as text so Qwen-VL processors do not load images.
        input_text = render_no_think_chat(
            tokenizer, messages, add_generation_prompt=True
        )
        inputs = tokenize_text_only(tokenizer, input_text, model.device)
        input_len = inputs["input_ids"].shape[1]

        # Generate
        with torch.no_grad():
            outputs = model.generate(
                **inputs,
                max_new_tokens=max_new_tokens,
                do_sample=do_sample,
                temperature=temperature,
                top_p=top_p,
                pad_token_id=tokenizer.eos_token_id,
            )
        generated_text = tokenizer.decode(
            outputs[0][input_len:], skip_special_tokens=True
        )

        # Strip TRACE
        generated_text = re.sub(
            '\x3cthink\x3e.*?\x3c/think\x3e', '',
            generated_text, flags=re.DOTALL
        ).strip()

        # Parse action
        action = parse_action(generated_text)

        # Compute log_prob for the generated tokens (for REINFORCE)
        # We'll compute this properly in the training loop using the
        # full sequence. For now, store the generated token IDs.
        # The train.py will compute log_probs during the loss step.
        generated_ids = outputs[0][input_len:]

        # Step environment (even if parse failed — NO_OP fallback)
        step_resp = client.step(
            action.action_type, action.target_node_id, action.parameter
        )
        obs_dict = step_resp.get("observation", step_resp)
        step_reward = step_resp.get("reward", 0.0)
        episode_reward = step_reward
        done = step_resp.get("done", False)
        sla_violations = obs_dict.get("sla_violations", sla_violations)

        # Record transition
        transition = Transition(
            obs_text=obs_text,
            input_ids=inputs["input_ids"].squeeze(0),
            attention_mask=inputs["attention_mask"].squeeze(0),
            action=action,
            reward=step_reward,
        )
        episode.transitions.append(transition)

        if not action.is_valid:
            episode.num_invalid += 1

        if done:
            episode.done = True
            break

    episode.finalize()
    return episode


# ────────────────────────────────────────────────
# Heuristic Baseline
# ────────────────────────────────────────────────

def heuristic_action(obs_dict: Dict, task_id: str, step: int = 0,
                    max_steps: int = 60,
                    episode_reward: float = 0.0) -> Tuple[str, str, float]:
    """Task-aware, reward-aware heuristic with balanced action distribution."""
    nodes = obs_dict.get("nodes", [])
    if not nodes:
        return "NO_OP", "node-0", 0.0
    node_map = {n["node_id"]: n for n in nodes}

    total_queue = sum(n["queue_depth"] * 200 for n in nodes)
    avg_latency = sum(n["latency_ms"] for n in nodes) / len(nodes)
    failed_nodes = [n for n in nodes if n.get("status") == "FAILED"]
    degraded_nodes = [n for n in nodes if n.get("status") == "DEGRADED"]

    progress = step / max_steps if max_steps > 0 else 0
    early = progress < 0.15
    late = progress > 0.65

    # ── TASK-2: Fault tolerance ──
    if task_id == "task-2":
        if failed_nodes:
            fn = failed_nodes[0]
            starved_children = [
                n for n in nodes
                if n.get("status") == "DEGRADED" and n["node_id"] not in CRITICAL_NODES
            ]
            if starved_children and step % 3 != 0:
                target = max(starved_children, key=lambda n: n["queue_depth"])
                return "SCALE_UP", target["node_id"], 0.5
            return "REROUTE_TRAFFIC", fn["node_id"], 0.7

        if episode_reward > 0.5 and avg_latency < 0.04:
            non_vips = [n for n in nodes
                        if not n.get("is_vip", False) and n.get("status") != "FAILED"]
            overprov = [n for n in non_vips if n.get("capacity", 0) > 0.7]
            if overprov:
                target = max(overprov, key=lambda n: n.get("capacity", 0))
                return "SCALE_DOWN", target["node_id"], 0.3
            return "NO_OP", "node-0", 0.0

        if avg_latency > 0.04 or total_queue > 100:
            downstream = [n for n in nodes
                          if n["node_id"] != "node-0" and n.get("status") != "FAILED"]
            if downstream:
                target = max(downstream, key=lambda n: (
                    n.get("status") == "DEGRADED", n["queue_depth"]))
                return "SCALE_UP", target["node_id"], 0.4

        return "NO_OP", "node-0", 0.0

    # ── TASK-3: Surge on node-1/2 ──
    if task_id == "task-3":
        n1 = node_map.get("node-1", {})
        n2 = node_map.get("node-2", {})
        n3 = node_map.get("node-3", {})
        n4 = node_map.get("node-4", {})

        if n1.get("queue_depth", 0) > 0.3:
            param = 0.6 if n1["queue_depth"] > 0.7 else 0.4
            return "SCALE_UP", "node-1", param
        if n2.get("queue_depth", 0) > 0.3:
            param = 0.6 if n2["queue_depth"] > 0.7 else 0.4
            return "SCALE_UP", "node-2", param

        for nid, nd in [("node-3", n3), ("node-4", n4)]:
            if nd.get("queue_depth", 0) > 0.5 and nd.get("status") != "FAILED":
                return "SHED_LOAD", nid, 0.4

        if avg_latency < 0.04 and total_queue < 80:
            for nid in ["node-1", "node-2"]:
                n = node_map.get(nid, {})
                if n.get("capacity", 0) > 0.8:
                    return "SCALE_DOWN", nid, 0.3

        if episode_reward > 0.5 or (avg_latency < 0.04 and total_queue < 80):
            return "NO_OP", "node-0", 0.0

        if total_queue > 60:
            for nid in ["node-1", "node-2"]:
                n = node_map.get(nid, {})
                if n.get("queue_depth", 0) > 0.15 and n.get("status") != "FAILED":
                    return "SCALE_UP", nid, 0.3

        return "NO_OP", "node-0", 0.0

    # ── TASK-1: Traffic ramp ──
    if early and avg_latency < 0.03 and total_queue < 60:
        return "NO_OP", "node-0", 0.0

    if episode_reward > 0.55 and avg_latency < 0.04 and total_queue < 100:
        non_vips = [n for n in nodes
                    if not n.get("is_vip", False) and n.get("status") != "FAILED"]
        overprov = [n for n in non_vips if n.get("capacity", 0) > 0.7]
        if overprov and total_queue < 60:
            target = max(overprov, key=lambda n: n.get("capacity", 0))
            return "SCALE_DOWN", target["node_id"], 0.3
        return "NO_OP", "node-0", 0.0

    if late and avg_latency < 0.035 and total_queue < 80:
        non_vips = [n for n in nodes
                    if not n.get("is_vip", False) and n.get("status") != "FAILED"]
        overprov = [n for n in non_vips if n.get("capacity", 0) > 0.7]
        if overprov:
            target = max(overprov, key=lambda n: n.get("capacity", 0))
            return "SCALE_DOWN", target["node_id"], 0.3
        return "NO_OP", "node-0", 0.0

    non_critical_overloaded = [
        n for n in nodes
        if n["queue_depth"] > 0.5 and n["node_id"] not in CRITICAL_NODES
        and n.get("status") != "FAILED"
    ]
    if non_critical_overloaded and avg_latency > 0.05:
        target = non_critical_overloaded[0]
        return "SHED_LOAD", target["node_id"], 0.4

    if avg_latency > 0.04 or total_queue > 100:
        downstream = [n for n in nodes
                      if n["node_id"] != "node-0" and n.get("status") != "FAILED"]
        if downstream:
            target = max(downstream, key=lambda n: (
                n.get("status") == "DEGRADED", n["queue_depth"]))
        else:
            target = node_map.get("node-0", nodes[0])
        param = 0.6 if target["queue_depth"] > 0.75 else 0.4
        return "SCALE_UP", target["node_id"], param

    return "NO_OP", "node-0", 0.0


def rollout_heuristic_episode(
    client: OpenEnvClient,
    task_id: str,
    max_steps: int,
    seed: Optional[int] = None,
) -> Episode:
    """Run one episode using the heuristic baseline."""
    episode = Episode(task_id=task_id)

    reset_resp = client.reset(task_id=task_id, seed=seed)
    obs_dict = reset_resp.get("observation", reset_resp)
    episode_reward = 0.0

    for step in range(1, max_steps + 1):
        action_type, target_node_id, parameter = heuristic_action(
            obs_dict, task_id, step=step, max_steps=max_steps,
            episode_reward=episode_reward,
        )
        step_resp = client.step(action_type, target_node_id, parameter)
        obs_dict = step_resp.get("observation", step_resp)
        step_reward = step_resp.get("reward", 0.0)
        episode_reward = step_reward
        done = step_resp.get("done", False)

        action = ParsedAction(action_type, target_node_id, parameter)
        episode.transitions.append(Transition(
            obs_text="", input_ids=None, attention_mask=None,
            action=action, reward=step_reward,
        ))

        if done:
            episode.done = True
            break

    episode.finalize()
    return episode