"""LLM adapter interface and concrete implementations.

* **generate_section** — LangChain LCEL: ``RICS_PROMPT | ChatOpenAI | StrOutputParser``
  with the same rich prompts as before (style profile, creativity hint, temperature).
* **proofread** / **enhance** — OpenAI Chat Completions API (unchanged behaviour).
"""

import logging
from abc import ABC, abstractmethod
from typing import TYPE_CHECKING

from app.config import settings
from app.generator.prompts import (
    ENHANCE_SYSTEM_PROMPT,
    PROOFREAD_SYSTEM_PROMPT,
    RICS_PROMPT,
    VALIDATE_SYSTEM_PROMPT,
    build_enhance_prompt,
    build_lcel_invoke_vars,
    build_proofread_prompt,
    build_validate_prompt,
    max_context_tokens_for_survey_level,
    max_output_tokens_for_survey_level,
    top_p_for_ai_involvement,
)

if TYPE_CHECKING:
    from app.models.schemas import WritingStyleProfile

logger = logging.getLogger(__name__)


class LLMAdapter(ABC):
    """Abstract interface for all three LLM generation modes.

    Example::

        adapter = get_llm_adapter()
        text = adapter.generate_section(
            skeleton="[Location]: [description].",
            bullets=["Semi-detached, NW3", "95 sqm"],
            snippets=["The property is located near…"],
        )
    """

    @abstractmethod
    def generate_section(
        self,
        skeleton: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
        document_context: list[str] | None = None,
        style_anchor: str | None = None,
        hierarchy_section_snippets: list[str] | None = None,
        paragraph_snippets: list[str] | None = None,
        identity_facts: str | None = None,
        survey_level: int | None = None,
        reference_only_context: bool = False,
        ai_percent: int | None = None,
        interference_level: str | None = None,
        scope_fence: str | None = None,
    ) -> str:
        """Adapt ``skeleton`` using ``bullets`` as facts and ``snippets`` as examples.

        Args:
            skeleton: RICS section template with placeholder markers.
            bullets: Ordered list of user-supplied fact bullets.
            snippets: Fine-grained evidence when ``paragraph_snippets`` is omitted (backward compatible).
            style_profile: Optional detected writing style; applied when present.
            temperature: LLM sampling temperature (controlled by ai_level).
            creativity_hint: Short instruction appended to the user prompt.
            document_context: Optional broader excerpts (whole-PDF / report narrative).
            style_anchor: Optional surveyor draft paragraph for tone and structure.
            hierarchy_section_snippets: Mid-tier passages (e.g. page / section scope).
            paragraph_snippets: Paragraph-tier evidence; defaults to ``snippets`` when unset.
            identity_facts: Optional pinned identity block (address / property type / occupancy) that must remain consistent.
            interference_level: Optional qualitative mode (minimum | medium | maximum) for prompts and budgets.

        Returns:
            Plain-text adapted section (no placeholders; missing facts are stated explicitly).
        """
        ...

    @abstractmethod
    def proofread(
        self,
        text: str,
        bullets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.15,
        creativity_hint: str = "",
    ) -> str:
        """Review ``text`` for grammar, clarity, and style consistency.

        Args:
            text: Previously generated section text to proofread.
            bullets: Original fact bullets (factual reference).
            style_profile: Detected writing style profile.
            temperature: LLM sampling temperature (controlled by ai_level).
            creativity_hint: Short instruction appended to the user prompt.

        Returns:
            Corrected text followed by ``---NOTES---`` and brief editor notes.
        """
        ...

    @abstractmethod
    def enhance(
        self,
        text: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
    ) -> str:
        """Expand ``text`` with additional technical depth from ``snippets``.

        Args:
            text: Existing section text to enrich.
            bullets: Original fact bullets (primary trusted source).
            snippets: Additional retrieved chunks for technical enrichment.
            style_profile: Detected writing style profile.
            temperature: LLM sampling temperature (controlled by ai_level).
            creativity_hint: Short instruction appended to the user prompt.

        Returns:
            Enhanced plain-text section (no placeholders; missing facts are stated explicitly).
        """
        ...

    @abstractmethod
    def validate_section_compliance(
        self,
        *,
        survey_level: int | None,
        section_code: str,
        bullets: list[str],
        evidence_snippets: list[str],
        text: str,
    ) -> str:
        """Return "PASS" or "FAIL: ..." for survey-level compliance."""
        ...

    @abstractmethod
    def constrained_weave(
        self,
        *,
        section_code: str,
        section_title: str | None,
        bullets: list[str],
        standard_passages: list[str],
        survey_level: int | None = None,
    ) -> str:
        """Structural-router LLM call for ``ai_percent == 0``.

        Takes the firm's RAG-retrieved STANDARD PASSAGES and the inspector's
        RAW NOTES (``bullets``) and produces the standard wording with the
        notes' specifics woven into the appropriate slots — no creative
        writing, no new sentences. Returns plain text or "" on failure.
        """
        ...


class OpenAIAdapter(LLMAdapter):
    """Generate mode via LangChain LCEL; proofread/enhance via OpenAI Chat Completions."""

    def __init__(self) -> None:
        from langchain_openai import ChatOpenAI
        from openai import OpenAI

        self._client = OpenAI(api_key=settings.openai_api_key)
        self._model = settings.chat_model
        self._lc_llm = ChatOpenAI(
            model=self._model,
            temperature=0.2,
            max_tokens=settings.max_output_tokens,
            api_key=settings.openai_api_key,
            max_retries=3,
        )

    def _call(
        self,
        system: str,
        user: str,
        max_tokens: int | None = None,
        temperature: float = 0.2,
        *,
        phase: str = "chat",
        survey_level: int | None = None,
        interference_level: str | None = None,
        tenant_id: str | None = None,
        section_id: str | None = None,
    ) -> str:
        """Make a single Chat Completions call and return the text."""
        from app.llm.llm_throttle import throttled_sync_llm_call
        from app.llm.prompt_cache import (
            build_chat_messages,
            log_openai_cache_usage,
            openai_extra_kwargs,
            prompt_caching_active,
        )

        messages = build_chat_messages(system=system, user=user)
        extra = openai_extra_kwargs(
            phase=phase,
            model=self._model,
            survey_level=survey_level,
            interference_level=interference_level,
            tenant_id=tenant_id,
        )

        def _invoke():
            response = self._client.chat.completions.create(
                model=self._model,
                messages=messages,
                max_tokens=max_tokens or settings.max_output_tokens,
                temperature=temperature,
                **extra,
            )
            if prompt_caching_active():
                log_openai_cache_usage(response, phase=phase, section_id=section_id)
            return (response.choices[0].message.content or "").strip()

        return throttled_sync_llm_call(phase=phase, section_id=section_id, call=_invoke)

    def generate_section(
        self,
        skeleton: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
        document_context: list[str] | None = None,
        style_anchor: str | None = None,
        hierarchy_section_snippets: list[str] | None = None,
        paragraph_snippets: list[str] | None = None,
        identity_facts: str | None = None,
        survey_level: int | None = None,
        reference_only_context: bool = False,
        ai_percent: int | None = None,
        interference_level: str | None = None,
        tenant_id: str | None = None,
        scope_fence: str | None = None,
    ) -> str:
        from langchain_core.output_parsers import StrOutputParser

        fine = paragraph_snippets if paragraph_snippets is not None else snippets

        # Tier-aware budgets. Previously the LCEL chain was bound to
        # `settings.max_output_tokens` at construct time (default 300), so
        # *every* section — Level 1 condition note, Level 2 buyer summary,
        # Level 3 diagnostic narrative — was capped at the same ~225-word
        # ceiling. The prompt's word target for L3 is now 300–700 words; the
        # adapter has to be allowed to actually emit that. We rebind both
        # context (input-side) and max_tokens (output-side) per call so a
        # single shared adapter instance can serve all tiers without sharing
        # an L1-sized output budget.
        out_tokens = max_output_tokens_for_survey_level(
            survey_level, interference_level=interference_level
        )
        ctx_tokens = max_context_tokens_for_survey_level(
            survey_level, interference_level=interference_level
        )
        vars_ = build_lcel_invoke_vars(
            skeleton=skeleton,
            bullets=bullets,
            snippets=None,
            max_context_tokens=ctx_tokens,
            style_profile=style_profile,
            creativity_hint=creativity_hint,
            document_snippets=document_context,
            section_snippets=None,
            hierarchy_section_snippets=hierarchy_section_snippets,
            paragraph_snippets=fine,
            style_anchor=style_anchor,
            identity_facts=identity_facts,
            survey_level=survey_level,
            reference_only_context=reference_only_context,
            ai_percent=ai_percent,
            interference_level=interference_level,
            scope_fence=scope_fence,
        )
        top_p = top_p_for_ai_involvement(ai_percent)
        from app.llm.prompt_cache import (
            build_chat_messages,
            log_openai_cache_usage,
            openai_extra_kwargs,
            prompt_caching_active,
        )

        if prompt_caching_active():
            from app.llm.llm_throttle import throttled_sync_llm_call

            extra = openai_extra_kwargs(
                phase="generate_section",
                model=self._model,
                survey_level=survey_level,
                interference_level=interference_level,
                tenant_id=tenant_id,
            )

            def _invoke() -> str:
                response = self._client.chat.completions.create(
                    model=self._model,
                    messages=build_chat_messages(
                        system=str(vars_.get("system_content") or ""),
                        user=str(vars_.get("user_content") or ""),
                    ),
                    max_tokens=out_tokens,
                    temperature=temperature,
                    top_p=top_p,
                    **extra,
                )
                log_openai_cache_usage(response, phase="generate_section", section_id=None)
                return (response.choices[0].message.content or "").strip()

            text = throttled_sync_llm_call(
                phase="generate_section", section_id=None, call=_invoke
            )
        else:
            from langchain_core.output_parsers import StrOutputParser

            chain = (
                RICS_PROMPT
                | self._lc_llm.bind(temperature=temperature, max_tokens=out_tokens, top_p=top_p)
                | StrOutputParser()
            )
            # Sync adapter runs inside run_sync_in_executor from generation_facade.
            text = (chain.invoke(vars_) or "").strip()
        logger.debug(
            "generate_section (LCEL): %d chars (model=%s, temp=%.3f, top_p=%.2f, max_out=%d, ctx=%d, lvl=%s)",
            len(text), self._model, temperature, top_p, out_tokens, ctx_tokens, survey_level,
        )
        return text

    def proofread(
        self,
        text: str,
        bullets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.15,
        creativity_hint: str = "",
    ) -> str:
        user_prompt = build_proofread_prompt(
            text=text,
            bullets=bullets,
            style_profile=style_profile,
            creativity_hint=creativity_hint,
        )
        # Proofread output should fit the input it's correcting. A 600-token
        # cap here truncated proofread output of long L3 sections. We size
        # the cap to the input length plus a small margin so proofread can
        # never *shrink* the user's text just because of a fixed budget.
        from app.chunking.splitter import count_tokens
        out_cap = max(700, min(2400, count_tokens(text or "") + 200))
        result = self._call(PROOFREAD_SYSTEM_PROMPT, user_prompt, max_tokens=out_cap, temperature=temperature)
        logger.debug("proofread: %d chars output (cap=%d)", len(result), out_cap)
        return result

    def enhance(
        self,
        text: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
    ) -> str:
        user_prompt = build_enhance_prompt(
            text=text,
            bullets=bullets,
            snippets=snippets,
            max_context_tokens=settings.max_context_tokens,
            style_profile=style_profile,
            creativity_hint=creativity_hint,
        )
        # Enhance is supposed to *add* technical depth, so it must be allowed
        # to grow well past the input. 500 tokens (~375 words) caps enhance
        # at less than a paragraph of new content for L3 sections — defeats
        # the purpose. Match generate-mode's tier ceiling instead.
        from app.chunking.splitter import count_tokens
        out_cap = max(900, min(2400, count_tokens(text or "") + 800))
        result = self._call(ENHANCE_SYSTEM_PROMPT, user_prompt, max_tokens=out_cap, temperature=temperature)
        logger.debug("enhance: %d chars output (cap=%d)", len(result), out_cap)
        return result

    def validate_section_compliance(
        self,
        *,
        survey_level: int | None,
        section_code: str,
        bullets: list[str],
        evidence_snippets: list[str],
        text: str,
    ) -> str:
        user_prompt = build_validate_prompt(
            survey_level=survey_level,
            section_code=section_code,
            bullets=bullets,
            evidence_snippets=evidence_snippets,
            text=text,
        )
        result = self._call(VALIDATE_SYSTEM_PROMPT, user_prompt, max_tokens=220, temperature=0.0)
        return (result or "").strip()

    def constrained_weave(
        self,
        *,
        section_code: str,
        section_title: str | None,
        bullets: list[str],
        standard_passages: list[str],
        survey_level: int | None = None,
        tenant_id: str | None = None,
    ) -> str:
        from app.generator.prompts import _ASSEMBLY_SYSTEM_CORE  # tier-aware
        from app.llm.llm_throttle import throttled_sync_llm_call
        from app.llm.prompt_cache import (
            build_chat_messages,
            log_openai_cache_usage,
            openai_extra_kwargs,
            prompt_caching_active,
        )

        cleaned_passages = [str(p).strip() for p in (standard_passages or []) if str(p).strip()]
        cleaned_bullets = [str(b).strip() for b in (bullets or []) if str(b).strip()]
        if not cleaned_passages or not cleaned_bullets:
            return ""

        title_part = f" — {section_title}" if section_title else ""
        user = (
            f"SECTION: {section_code}{title_part}\n\n"
            "STANDARD SOURCE PASSAGES (preserve wording; weave NOTES facts into the slots):\n"
            + "\n".join(f"- {p}" for p in cleaned_passages)
            + "\n\nINSPECTOR'S RAW NOTES (substitute these specifics into the standards):\n"
            + "\n".join(f"- {b}" for b in cleaned_bullets)
            + "\n\nProduce the structurally-routed output now. Standard wording stays, "
              "note facts replace generic slots, no new sentences, no new claims."
        )
        try:
            phase = "constrained_weave"
            extra = openai_extra_kwargs(
                phase=phase,
                model=self._model,
                survey_level=survey_level,
                tenant_id=tenant_id,
            )
            msgs = build_chat_messages(system=_ASSEMBLY_SYSTEM_CORE, user=user)

            def _invoke() -> str:
                response = self._client.chat.completions.create(
                    model=self._model,
                    messages=msgs,
                    max_tokens=600,
                    temperature=0.0,
                    top_p=0.1,
                    **extra,
                )
                if prompt_caching_active():
                    log_openai_cache_usage(response, phase=phase, section_id=section_code)
                return (response.choices[0].message.content or "").strip()

            return throttled_sync_llm_call(
                phase=phase, section_id=section_code, call=_invoke
            )
        except Exception as exc:  # noqa: BLE001
            logger.warning("constrained_weave failed: %s", exc)
            return ""


class MockLLMAdapter(LLMAdapter):
    """Deterministic mock adapter for tests and no-key environments.

    Accepts an optional ``response_override`` for injection in specific tests.

    Example::

        adapter = MockLLMAdapter(response_override="The property is a house.")
        text = adapter.generate_section(skeleton="", bullets=[], snippets=[])
        assert text == "The property is a house."
    """

    def __init__(self, response_override: str | None = None) -> None:
        self._override = response_override

    def generate_section(
        self,
        skeleton: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
        document_context: list[str] | None = None,
        style_anchor: str | None = None,
        hierarchy_section_snippets: list[str] | None = None,
        paragraph_snippets: list[str] | None = None,
        identity_facts: str | None = None,
        survey_level: int | None = None,
        reference_only_context: bool = False,
        ai_percent: int | None = None,
        interference_level: str | None = None,
        tenant_id: str | None = None,
        scope_fence: str | None = None,
    ) -> str:
        if self._override is not None:
            return self._override
        style_note = f" (style: {style_profile.tone})" if style_profile else ""
        summary = "; ".join(bullets[:3]) if bullets else "No facts provided"
        return f"Based on the available information{style_note}: {summary}."

    def proofread(
        self,
        text: str,
        bullets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.15,
        creativity_hint: str = "",
    ) -> str:
        return (
            f"{text}\n---NOTES---\n"
            "No OpenAI key configured — proofreading not available in mock mode. "
            "Add OPENAI_API_KEY to your .env file to enable real proofreading."
        )

    def enhance(
        self,
        text: str,
        bullets: list[str],
        snippets: list[str],
        style_profile: "WritingStyleProfile | None" = None,
        temperature: float = 0.2,
        creativity_hint: str = "",
    ) -> str:
        extra = f" Additional context from {len(snippets)} retrieved source(s) noted." if snippets else ""
        return (
            f"{text}{extra} "
            "[No OpenAI key configured — full technical enhancement requires OPENAI_API_KEY.]"
        )

    def validate_section_compliance(
        self,
        *,
        survey_level: int | None,
        section_code: str,
        bullets: list[str],
        evidence_snippets: list[str],
        text: str,
    ) -> str:
        return "PASS"

    def constrained_weave(
        self,
        *,
        section_code: str,
        section_title: str | None,
        bullets: list[str],
        standard_passages: list[str],
        survey_level: int | None = None,
        tenant_id: str | None = None,
    ) -> str:
        return ""  # mock returns empty; caller falls back to deterministic stitch


_llm_adapter_instance: LLMAdapter | None = None


def get_llm_adapter() -> LLMAdapter:
    """Return a singleton :class:`LLMAdapter`.

    The adapter is created once on first call and reused thereafter to avoid
    allocating a new ``openai.OpenAI`` connection pool on every generation call.

    Uses the real OpenAI adapter when ``settings.openai_api_key`` is set;
    falls back to the mock adapter otherwise.

    Returns:
        Configured :class:`LLMAdapter`.
    """
    global _llm_adapter_instance
    if _llm_adapter_instance is not None:
        return _llm_adapter_instance
    if settings.openai_api_key:
        _llm_adapter_instance = OpenAIAdapter()
    else:
        _llm_adapter_instance = MockLLMAdapter()
    return _llm_adapter_instance