"""
Component 8: Local chat interface using Gradio.

- Clean dark-themed UI.
- Prompt input box.
- Syntax-highlighted code output (Python + JavaScript).
- Copy button for each code response.
- Generation time + token count.
- Conversation history in session.
- Clear button to reset history.
- Live model selector: Base / LoRA / INT8 (no restart).
"""

from __future__ import annotations

import html
import re
import time
from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple

import gradio as gr
import torch
import torch.nn as nn
import yaml
from pygments import highlight
from pygments.formatters import HtmlFormatter
from pygments.lexers import JavascriptLexer, PythonLexer, TextLexer

from src.finetuning_system.lora_adapter import LoRAConfig, apply_lora, load_lora_state_dict
from src.inference_engine.inference_engine import DecodingConfig, InferenceEngine
from src.model_architecture.code_transformer import CodeTransformerLM, ModelConfig, get_model_presets
from src.tokenizer.code_tokenizer import CodeTokenizer


def _load_yaml(path: Path) -> Dict[str, Any]:
    if not path.exists():
        raise FileNotFoundError(f"Config file not found: {path}")
    data = yaml.safe_load(path.read_text(encoding="utf-8-sig"))
    if not isinstance(data, dict):
        raise ValueError("Invalid YAML format.")
    return data


def _build_model_config(path: Path) -> ModelConfig:
    cfg = _load_yaml(path)
    preset = cfg.get("preset")
    model_cfg = cfg.get("model", {})
    if preset:
        presets = get_model_presets()
        if preset not in presets:
            raise ValueError(f"Unknown preset: {preset}")
        merged = presets[preset].__dict__.copy()
        merged.update(model_cfg)
        return ModelConfig(**merged)
    return ModelConfig(**model_cfg)


def _guess_language(prompt: str, default_lang: str = "python") -> str:
    p = prompt.lower()
    if "javascript" in p or " js " in f" {p} " or "node" in p:
        return "javascript"
    if "python" in p:
        return "python"
    return default_lang


def _is_coding_prompt(prompt: str) -> bool:
    p = prompt.lower().strip()
    coding_keywords = [
        "code",
        "python",
        "javascript",
        "function",
        "bug",
        "error",
        "algorithm",
        "sort",
        "loop",
        "class",
        "api",
        "sql",
        "regex",
        "debug",
        "implement",
        "write",
    ]
    if any(k in p for k in coding_keywords):
        return True
    if re.fullmatch(r"(hi|hello|hey|yo|hola)[!. ]*", p):
        return False
    return False


def _highlight_code(code: str, language: str) -> str:
    code = code or ""
    if language == "javascript":
        lexer = JavascriptLexer()
    elif language == "python":
        lexer = PythonLexer()
    else:
        lexer = TextLexer()
    formatter = HtmlFormatter(nowrap=True)
    return highlight(code, lexer, formatter)


def _render_history(history: List[Dict[str, Any]]) -> str:
    formatter = HtmlFormatter(style="monokai")
    css = formatter.get_style_defs(".codehilite")
    blocks = [
        "<style>",
        css,
        """
        .chat-wrap { background: #0f1117; color: #e5e7eb; padding: 14px; border-radius: 12px; font-family: 'Segoe UI', sans-serif; }
        .entry { border: 1px solid #262a33; background: #151922; border-radius: 10px; padding: 12px; margin-bottom: 12px; }
        .prompt { color: #93c5fd; font-weight: 600; margin-bottom: 8px; white-space: pre-wrap; }
        .meta { color: #9ca3af; font-size: 12px; margin-top: 8px; }
        .code-box { border: 1px solid #2f3542; border-radius: 8px; background: #0b0d12; overflow-x: auto; }
        .code-inner { padding: 12px; font-family: Consolas, 'Courier New', monospace; font-size: 13px; line-height: 1.5; white-space: pre; }
        .copy-btn { background: #1f2937; color: #e5e7eb; border: 1px solid #374151; border-radius: 6px; padding: 5px 10px; cursor: pointer; float: right; margin-bottom: 6px; }
        .copy-btn:hover { background: #374151; }
        .label { font-size: 12px; color: #a1a1aa; margin-bottom: 6px; }
        """,
        "</style>",
        """
        <script>
        function copyCode(id) {
          const el = document.getElementById(id);
          if (!el) return;
          const text = el.innerText;
          navigator.clipboard.writeText(text);
        }
        </script>
        """,
        '<div class="chat-wrap">',
    ]

    if not history:
        blocks.append('<div class="entry"><div class="meta">No messages yet. Ask a coding question to begin.</div></div>')

    for i, item in enumerate(history, start=1):
        lang = item.get("language", "python")
        prompt = html.escape(str(item.get("prompt", "")))
        highlighted = _highlight_code(str(item.get("code", "")), lang)
        code_id = f"code-{i}"
        syntax_ok = "yes" if item.get("syntax_ok", False) else "n/a"
        mode = item.get("mode", "base")
        blocks.append('<div class="entry">')
        blocks.append(f'<div class="prompt">User: {prompt}</div>')
        blocks.append(f'<div class="label">Assistant ({lang})</div>')
        blocks.append(f'<button class="copy-btn" onclick="copyCode(\'{code_id}\')">Copy</button>')
        blocks.append('<div style="clear: both"></div>')
        blocks.append('<div class="code-box">')
        blocks.append(f'<pre class="code-inner codehilite" id="{code_id}">{highlighted}</pre>')
        blocks.append('</div>')
        blocks.append(
            f'<div class="meta">mode={mode} | time={item.get("time_sec", 0):.2f}s | '
            f'tokens={item.get("tokens", 0)} | syntax_ok={syntax_ok} | '
            f'attempt={item.get("attempt", 1)}</div>'
        )
        blocks.append('</div>')

    blocks.append('</div>')
    return "\n".join(blocks)


class ChatRuntime:
    def __init__(self, config_path: str) -> None:
        self.project_root = Path(__file__).resolve().parents[2]
        self.cfg = _load_yaml(self.project_root / config_path)

        self.model_cfg = _build_model_config(self.project_root / self.cfg["model"]["model_config_path"])
        self.cuda_device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
        if self.cuda_device.type != "cuda":
            raise RuntimeError("CUDA GPU is required for this chat interface setup.")

        self.tokenizer = CodeTokenizer.load(str(self.project_root / self.cfg["model"]["tokenizer_dir"]))

        self.decode_cfg = DecodingConfig(
            max_new_tokens=int(self.cfg["inference"].get("max_new_tokens", 300)),
            greedy_temperature=float(self.cfg["inference"].get("greedy_temperature", 0.0)),
            retry2_temperature=float(self.cfg["inference"].get("retry2_temperature", 0.25)),
            retry2_top_p=float(self.cfg["inference"].get("retry2_top_p", 0.85)),
            retry3_temperature=float(self.cfg["inference"].get("retry3_temperature", 0.35)),
            retry3_top_p=float(self.cfg["inference"].get("retry3_top_p", 0.90)),
            max_retries=int(self.cfg["inference"].get("max_retries", 3)),
            min_tokens_before_stop_check=int(self.cfg["inference"].get("min_tokens_before_stop_check", 64)),
        )

        self.current_mode: Optional[str] = None
        self.engine: Optional[InferenceEngine] = None

    def _release_current(self) -> None:
        self.engine = None
        self.current_mode = None
        if torch.cuda.is_available():
            torch.cuda.empty_cache()

    def _current_vram_gb(self) -> float:
        if not torch.cuda.is_available():
            return 0.0
        return float(torch.cuda.memory_allocated() / (1024**3))

    def _status_text(self, mode: str, load_sec: float) -> str:
        return f"MINDI 1.0 420M | mode={mode} | load={load_sec:.2f}s | vram={self._current_vram_gb():.2f}GB"

    def _load_base_model(self) -> InferenceEngine:
        model = CodeTransformerLM(self.model_cfg).to(self.cuda_device)
        payload = torch.load(self.project_root / self.cfg["model"]["base_checkpoint_path"], map_location=self.cuda_device)
        model.load_state_dict(payload["model_state"])
        model.half()
        return InferenceEngine(model=model, tokenizer=self.tokenizer, device=self.cuda_device)

    def _load_lora_model(self) -> InferenceEngine:
        model = CodeTransformerLM(self.model_cfg).to(self.cuda_device)
        payload = torch.load(self.project_root / self.cfg["model"]["base_checkpoint_path"], map_location=self.cuda_device)
        model.load_state_dict(payload["model_state"])

        lora_cfg = LoRAConfig(
            r=int(self.cfg.get("lora", {}).get("r", 8)),
            alpha=int(self.cfg.get("lora", {}).get("alpha", 16)),
            dropout=float(self.cfg.get("lora", {}).get("dropout", 0.05)),
            target_keywords=list(self.cfg.get("lora", {}).get("target_keywords", ["q_proj", "k_proj", "v_proj", "o_proj", "fc1", "fc2"])),
        )
        apply_lora(model, lora_cfg)
        model = model.to(self.cuda_device)

        lora_payload = torch.load(self.project_root / self.cfg["model"]["lora_adapter_path"], map_location=self.cuda_device)
        lora_state = lora_payload.get("lora_state", lora_payload)
        load_lora_state_dict(model, lora_state)
        model.half()
        return InferenceEngine(model=model, tokenizer=self.tokenizer, device=self.cuda_device)

    def _load_int8_model(self) -> InferenceEngine:
        cpu = torch.device("cpu")
        model = CodeTransformerLM(self.model_cfg).to(cpu).float()
        model = torch.quantization.quantize_dynamic(model, {nn.Linear}, dtype=torch.qint8)
        q_state = torch.load(self.project_root / self.cfg["model"]["quantized_state_path"], map_location=cpu)
        model.load_state_dict(q_state)
        return InferenceEngine(model=model, tokenizer=self.tokenizer, device=cpu)

    def _ensure_mode(self, mode: str) -> str:
        mode = (mode or "base").lower().strip()
        if mode not in {"base", "lora", "int8"}:
            mode = "base"

        if self.current_mode == mode and self.engine is not None:
            return self._status_text(mode, load_sec=0.0)

        t0 = time.perf_counter()
        self._release_current()
        if mode == "base":
            self.engine = self._load_base_model()
        elif mode == "lora":
            self.engine = self._load_lora_model()
        else:
            self.engine = self._load_int8_model()

        self.current_mode = mode
        load_sec = time.perf_counter() - t0
        return self._status_text(mode, load_sec=load_sec)

    def switch_mode(self, mode: str) -> str:
        return self._ensure_mode(mode)

    def respond(self, prompt: str, history: List[Dict[str, Any]], mode: str) -> Tuple[str, List[Dict[str, Any]], str, str]:
        prompt = (prompt or "").strip()
        if not prompt:
            status = self._ensure_mode(mode)
            return _render_history(history), history, "", status

        status = self._ensure_mode(mode)

        if not _is_coding_prompt(prompt):
            fallback = "Please ask a coding question (for example: 'Write a Python function to ...' or 'Fix this JavaScript bug ...')."
            history.append(
                {
                    "prompt": prompt,
                    "code": fallback,
                    "language": "text",
                    "tokens": 0,
                    "time_sec": 0.0,
                    "syntax_ok": None,
                    "attempt": 0,
                    "mode": self.current_mode or "base",
                }
            )
            return _render_history(history), history, "", status

        lang_default = str(self.cfg["inference"].get("language_default", "python"))
        language = _guess_language(prompt, default_lang=lang_default)

        start = time.perf_counter()
        result = self.engine.generate_with_retry(prompt=prompt, language=language, cfg=self.decode_cfg)  # type: ignore[union-attr]
        elapsed = time.perf_counter() - start

        final = result["final"]
        history.append(
            {
                "prompt": prompt,
                "code": final["code"],
                "language": language,
                "tokens": int(final.get("generated_tokens", 0)),
                "time_sec": float(elapsed),
                "syntax_ok": bool(final.get("syntax_ok", False)) if language == "python" else None,
                "attempt": int(final.get("attempt", 1)),
                "mode": self.current_mode or "base",
            }
        )

        return _render_history(history), history, "", status

    def clear(self, mode: str) -> Tuple[str, List[Dict[str, Any]], str, str]:
        history: List[Dict[str, Any]] = []
        status = self._ensure_mode(mode)
        return _render_history(history), history, "", status


def create_demo(config_path: str = "configs/component8_chat_config.yaml") -> gr.Blocks:
    runtime = ChatRuntime(config_path=config_path)

    with gr.Blocks(title="MINDI 1.0 420M", theme=gr.themes.Base()) as demo:
        gr.Markdown("## MINDI 1.0 420M\nYour local coding intelligence — 420M parameters, fully offline")

        history_state = gr.State([])
        chat_html = gr.HTML(value=_render_history([]))

        with gr.Row():
            mode_dropdown = gr.Dropdown(
                label="Model Mode",
                choices=["base", "lora", "int8"],
                value="base",
                interactive=True,
            )
            status_box = gr.Textbox(label="Status", value="MINDI 1.0 420M | mode=base | load=0.00s | vram=0.00GB", interactive=False)

        prompt_box = gr.Textbox(
            label="Your Prompt",
            lines=4,
            placeholder="Ask MINDI anything about code",
        )

        with gr.Row():
            send_btn = gr.Button("Generate", variant="primary")
            clear_btn = gr.Button("Clear Conversation")
            switch_btn = gr.Button("Apply Mode")

        switch_btn.click(fn=runtime.switch_mode, inputs=[mode_dropdown], outputs=[status_box])

        send_btn.click(
            fn=runtime.respond,
            inputs=[prompt_box, history_state, mode_dropdown],
            outputs=[chat_html, history_state, prompt_box, status_box],
            queue=True,
        )
        prompt_box.submit(
            fn=runtime.respond,
            inputs=[prompt_box, history_state, mode_dropdown],
            outputs=[chat_html, history_state, prompt_box, status_box],
            queue=True,
        )
        clear_btn.click(
            fn=runtime.clear,
            inputs=[mode_dropdown],
            outputs=[chat_html, history_state, prompt_box, status_box],
        )

    return demo