"""التحقق من هلوسة القرآن والحديث وتصحيحها: Gradio interface.

    python app.py                      # http://127.0.0.1:7860

Mode A verifies pasted text with the chosen detection engine. Mode B ("ask then verify") sends the question to a single
pre-configured OpenAI client and verifies the answer; the key comes from the OPENAI_API_KEY environment variable only
(never from the form, never from the repository). The in-browser page (build_static_space.py) shares these handlers.
"""
from __future__ import annotations

import json
import logging
import os
import threading
from pathlib import Path
from typing import List, Optional

import ui
from camelbert_adapter import analyze_with_spans, entities_to_spans, query_hosted_model, simulate_spans
from llm_client import LLMError, generate
from verifier import MAX_INPUT_CHARS, IslamicContentVerifier

logger = logging.getLogger(__name__)

EXAMPLES_PATH = Path(__file__).resolve().parent / "demo" / "examples.json"

# Detection engines offered in the UI (English labels by design; the first is the default).
ENGINES = [
    ("Standard · Rules + Corpus Scan", "standard"),
    ("CAMeLBERT-MSA · Fine-tuned (Hugging Face)", "camelbert"),
]

_pipeline: Optional[IslamicContentVerifier] = None
_lock = threading.Lock()


def get_pipeline() -> IslamicContentVerifier:
    """Created once. The Quran index loads immediately; the Hadith index loads lazily (see ``warm_in_background``)."""
    global _pipeline
    with _lock:
        if _pipeline is None:
            _pipeline = IslamicContentVerifier()
        return _pipeline


def warm_in_background() -> None:
    threading.Thread(target=lambda: get_pipeline().retriever.warm(), daemon=True).start()


def load_examples(path: Path = EXAMPLES_PATH) -> List[dict]:
    try:
        with open(path, encoding="utf-8") as handle:
            return json.load(handle)
    except (OSError, json.JSONDecodeError):
        logger.exception("Could not load demo examples from %s", path)
        return []


def _analyze(text: str, engine: str = "standard") -> dict:
    """Run the pipeline with the selected detection engine. The CAMeLBERT engine uses a hosted model when ``ICV_HF_MODEL``
    is set and reachable; otherwise it runs as a simulation on top of the bundled detector (and says so)."""
    pipeline = get_pipeline()
    if engine != "camelbert":
        return pipeline.analyze(text)
    model = os.environ.get("ICV_HF_MODEL", "").strip()
    if model:
        try:
            spans = query_hosted_model(text, model, os.environ.get("HF_TOKEN", ""))
            return analyze_with_spans(pipeline, text, spans, engine="camelbert")
        except RuntimeError:
            logger.warning("Hosted CAMeLBERT model unavailable; using the simulation")
    return analyze_with_spans(pipeline, text, simulate_spans(pipeline, text), engine="camelbert-simulated")


def verify_with_entities(text: str, entities_json: str, engine: str = "camelbert", generated: bool = False) -> str:
    """Browser path: the page called the hosted token-classification model and passes its raw entities here."""
    try:
        spans = entities_to_spans(text, json.loads(entities_json or "[]"))
        result = analyze_with_spans(get_pipeline(), text, spans, engine=engine)
        return ui.render_results(result, generated_answer=text if generated else None)
    except ValueError:
        return ui.render_message(f"النص طويل جدًا (الحد الأقصى {MAX_INPUT_CHARS} حرف).", "warn")
    except Exception:
        logger.exception("Verification with external spans failed")
        return ui.render_message("حدث خطأ غير متوقع أثناء التحقق.", "bad")


def verify_text(text: str, engine: str = "standard") -> str:
    """Mode A. Never raises: problems become Arabic notices."""
    if not text or not text.strip():
        return ui.render_message("الرجاء إدخال نص للتحقق منه.", "warn")
    try:
        return ui.render_results(_analyze(text, engine))
    except ValueError:
        return ui.render_message(f"النص طويل جدًا (الحد الأقصى {MAX_INPUT_CHARS} حرف).", "warn")
    except Exception:
        logger.exception("Verification failed")
        return ui.render_message("حدث خطأ غير متوقع أثناء التحقق.", "bad")


def verify_generated_answer(answer: str, engine: str = "standard") -> str:
    """Verify a model answer and show it above the report (also used by the in-browser page)."""
    try:
        return ui.render_results(_analyze(answer, engine), generated_answer=answer)
    except Exception:
        logger.exception("Verification of the generated answer failed")
        return ui.render_message("تعذّر التحقق من إجابة النموذج.", "bad")


def ask_then_verify(prompt: str, engine: str = "standard") -> str:
    """Mode B: ask the pre-configured OpenAI client, then verify every quotation in its answer."""
    try:
        answer = generate(None, prompt)
    except LLMError as exc:
        return ui.render_message(str(exc), "warn")
    return verify_generated_answer(answer, engine)


def build_interface():
    import gradio as gr

    examples = load_examples()

    def next_example(index: int):
        if not examples:
            return "", 0
        return examples[index % len(examples)]["text"], (index + 1) % len(examples)

    theme = gr.themes.Base(primary_hue="emerald", neutral_hue="stone")
    with gr.Blocks(title=ui.APP_TITLE, css=ui.CSS, theme=theme, head=f"<script>{ui.COPY_JS}</script>") as demo:
        gr.HTML(ui.HERO)
        with gr.Tabs():
            with gr.Tab("تحقّق مباشر"):
                example_index = gr.State(0)
                engine = gr.Dropdown(choices=ENGINES, value="standard", label="Detection engine", elem_classes="engine-select")
                text_input = gr.Textbox(label="النص المراد التحقق منه", lines=9, max_lines=24, placeholder=ui.PLACEHOLDER,
                                        rtl=True, elem_classes="input-area")
                with gr.Row():
                    verify_button = gr.Button("تحقّق من النص", variant="primary", scale=3)
                    example_button = gr.Button("جرّب مثالًا", variant="secondary", scale=2)
                results = gr.HTML(elem_classes="results")
                verify_button.click(verify_text, inputs=[text_input, engine], outputs=results)
                example_button.click(next_example, inputs=example_index, outputs=[text_input, example_index]).then(
                    verify_text, inputs=[text_input, engine], outputs=results)
            with gr.Tab("اسأل ثم تحقّق"):
                gr.HTML('<div class="icv"><div class="notice">اكتب سؤالًا، وسيجيب عنه النظام مباشرةً، ثم يفحص كل آية '
                        'وحديث ورد في الإجابة ويعرض الأخطاء والتصحيحات.</div></div>')
                prompt = gr.Textbox(label="سؤالك", lines=3, placeholder=ui.PROMPT_PLACEHOLDER, rtl=True, elem_classes="input-area")
                ask_button = gr.Button("اسأل ثم تحقّق", variant="primary")
                answer_results = gr.HTML(elem_classes="results")
                ask_button.click(ask_then_verify, inputs=[prompt, engine], outputs=answer_results)
        gr.HTML(ui.DISCLAIMER)
    return demo


def _load_dotenv(path: Path = Path(__file__).resolve().parent / ".env") -> None:
    """Minimal ``.env`` reader for local runs (no extra dependency); existing environment variables win."""
    try:
        lines = path.read_text(encoding="utf-8").splitlines()
    except OSError:
        return
    for line in lines:
        name, sep, value = line.strip().partition("=")
        if sep and name and not name.startswith("#") and value.strip():
            os.environ.setdefault(name.strip(), value.strip().strip('"').strip("'"))


def main() -> None:
    logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(name)s: %(message)s")
    _load_dotenv()
    get_pipeline()
    warm_in_background()
    build_interface().queue().launch(share=os.environ.get("ICV_SHARE") == "1")


if __name__ == "__main__":
    main()