"""HTTP/SSE delivery adapter for the protocol v3 workflow."""

from __future__ import annotations

import asyncio
from collections.abc import AsyncIterator
from hashlib import sha256
import re
import secrets
from typing import Any

from app.cad_agent.application.workflow import ModelIdentity
from app.cad_agent.application.capabilities import verify_model_capability
from app.cad_agent.composition import V3Services, compose_v3
from app.cad_agent.domain.errors import ErrorCode
from app.cad_agent.domain.state import TaskPhase, transition
from app.models.contracts import ChatMessage
from app.services.library import CdslLibrary
from app.services.sse import event
from app.services.storage import WorkspaceStore, now_iso
from app.settings import Settings


def text_from_message(message: ChatMessage) -> str:
    return "\n".join(part.text or "" for part in message.parts if part.type == "text").strip()


def _response_language(text: str) -> str:
    cjk = sum(1 for char in text if "\u4e00" <= char <= "\u9fff")
    latin = sum(1 for char in text if char.isascii() and char.isalpha())
    return "Chinese" if cjk >= 2 and cjk >= latin * 0.15 else "English"


_EVENT_LABELS = {
    "requirements_review": "需求合同独立复核",
    "action_selection": "动作选择",
    "tool_call": "建模工具",
    "candidate_result": "候选构建",
    "candidate_review": "候选独立复核",
    "final_review": "最终独立复核",
    "task_terminal": "生成任务",
    "state_changed": "任务状态",
}


def _visible_progress(name: str, payload: dict[str, Any]) -> dict[str, Any]:
    lifecycle = str(payload.get("lifecycle") or "")
    result = payload.get("result") if isinstance(payload.get("result"), dict) else {}
    status = "error" if lifecycle == "failed" or str(payload.get("status") or "") == "error" or str(result.get("status") or "") in {"rejected", "repair"} else "waiting" if lifecycle in {"waiting_for_user", "waiting_retry"} else "success" if lifecycle == "completed" else str(payload.get("status") or "running")
    return {**payload, "step": name, "label": _EVENT_LABELS.get(name, name), "status": status}


def _upsert_part(parts: list[dict[str, Any]], part: dict[str, Any]) -> None:
    part_id = str(part.get("id") or "")
    if part_id:
        for index, existing in enumerate(parts):
            if str(existing.get("id") or "") == part_id:
                parts[index] = part
                return
    parts.append(part)


class AgentService:
    """Delivery boundary: no CAD state transitions or provider calls live here."""

    def __init__(self, settings: Settings, store: WorkspaceStore, library: CdslLibrary) -> None:
        self.settings = settings
        self.store = store  # Conversation/attachment store, not v3 CAD state.
        self.library = library
        self.v3: V3Services = compose_v3(settings)
        self._autonomous_runs: dict[str, asyncio.Task[None]] = {}

    async def resume_running_tasks(self) -> None:
        task_ids = self.v3.repository.running_task_ids()
        if not task_ids:
            return
        try:
            author_provider, author_model = self.settings.resolve_model(None, None)
            review_provider, review_model = self.settings.resolve_independent_review_model(author_provider, author_model)
        except ValueError as error:
            await self._park_startup_tasks(
                task_ids,
                ErrorCode.MODEL_STRUCTURED_OUTPUT_UNSUPPORTED,
                str(error),
                retryable=False,
            )
            return
        try:
            author_capability = await verify_model_capability(
                self.v3.repository,
                self.v3.workflow.runtime,
                self.v3.models,
                provider_id=author_provider.id,
                model_id=author_model.id,
            )
            reviewer_capability = await verify_model_capability(
                self.v3.repository,
                self.v3.workflow.runtime,
                self.v3.models,
                provider_id=review_provider.id,
                model_id=review_model.id,
            )
        except Exception as error:
            # Startup recovery must never bypass a production capability gate.
            # Connectivity failures are recoverable, but they may not leave a
            # task falsely marked running without a worker.
            await self._park_startup_tasks(
                task_ids,
                ErrorCode.AUTHOR_TRANSPORT_UNAVAILABLE,
                str(error),
                retryable=True,
            )
            return
        if not author_capability.get("supported") or not reviewer_capability.get("supported"):
            await self._park_startup_tasks(
                task_ids,
                ErrorCode.MODEL_STRUCTURED_OUTPUT_UNSUPPORTED,
                "Selected author or reviewer did not pass the v3 conformance suite.",
                retryable=False,
            )
            return
        for task_id in task_ids:
            if task_id in self._autonomous_runs:
                continue
            self._autonomous_runs[task_id] = asyncio.create_task(
                self._consume_discarding(task_id, ModelIdentity(author_provider.id, author_model.id), ModelIdentity(review_provider.id, review_model.id)),
                name=f"resume-autonomous-cad-v3-{task_id}",
            )

    async def _park_startup_tasks(
        self,
        task_ids: list[str],
        error: ErrorCode,
        message: str,
        *,
        retryable: bool,
    ) -> None:
        """Make a failed startup gate durable instead of leaving phantom runs."""
        event_name = "waiting_retry" if retryable else "failed_model_capability"
        for task_id in task_ids:
            state = self.v3.repository.get_state(task_id)
            if state is None or task_id in self._autonomous_runs:
                continue
            try:
                next_state = transition(
                    state,
                    "waiting_retry" if retryable else "failed",
                    error=error,
                )
            except ValueError:
                continue
            if self.v3.repository.compare_and_swap(next_state, events=[{
                "event": event_name,
                "code": error.value,
                "message": message[:1000],
                "startup_recovery": True,
            }]):
                await self.v3.outbox.dispatch_pending(task_id=task_id)

    async def _consume_discarding(self, task_id: str, author: ModelIdentity, reviewer: ModelIdentity) -> None:
        try:
            async for _name, _payload in self.v3.workflow.run(task_id=task_id, author=author, reviewer=reviewer):
                # A resumed task has no active SSE client, but its durable
                # state events must still leave the transactional outbox.
                await self.v3.outbox.dispatch_pending(task_id=task_id)
        finally:
            # Flush a final transition emitted immediately before the worker
            # exits, such as WAITING_RETRY or FAILED_INTERNAL.
            await self.v3.outbox.dispatch_pending(task_id=task_id)
            self._autonomous_runs.pop(task_id, None)

    async def cancel(self, task_id: str) -> dict[str, Any] | None:
        state = self.v3.repository.get_state(task_id)
        if state is None:
            return None
        if state.phase not in {TaskPhase.COMPLETED, TaskPhase.FAILED, TaskPhase.CANCELLED}:
            cancelled = transition(state, "cancelled", error=ErrorCode.CANCELLED)
            if self.v3.repository.compare_and_swap(cancelled, events=[{
                "event": "task_cancelled",
                "from_phase": state.phase.value,
                "active_revision": state.active_revision,
                "checkpoint_preserved": bool(state.active_revision),
            }]):
                await self.v3.outbox.dispatch_pending(task_id=task_id)
        # Persist the terminal transition before interrupting the coroutine.
        # A concurrent worker will fail its optimistic CAS instead of reviving
        # the task after the caller has requested cancellation.
        running = self._autonomous_runs.pop(task_id, None)
        if running and not running.done():
            running.cancel()
        return self.v3.repository.get_task_projection(task_id)

    async def resume_retry(self, task_id: str) -> dict[str, Any] | None:
        """Explicitly restart one durably parked infrastructure retry.

        ``WAITING_FOR_USER`` is deliberately excluded: it requires new user
        input, while this endpoint is only the controlled recovery route for
        bounded provider/render/storage failures.
        """
        state = self.v3.repository.get_state(task_id)
        if state is None:
            return None
        if state.phase.value != "WAITING_RETRY":
            raise ValueError("Only a WAITING_RETRY CAD task can be resumed through this endpoint")
        running = self._autonomous_runs.get(task_id)
        if running is not None and not running.done():
            raise ValueError("The CAD task is already running")
        author_provider, author_model = self.settings.resolve_model(None, None)
        review_provider, review_model = self.settings.resolve_independent_review_model(author_provider, author_model)
        author_capability = await verify_model_capability(
            self.v3.repository,
            self.v3.workflow.runtime,
            self.v3.models,
            provider_id=author_provider.id,
            model_id=author_model.id,
        )
        reviewer_capability = await verify_model_capability(
            self.v3.repository,
            self.v3.workflow.runtime,
            self.v3.models,
            provider_id=review_provider.id,
            model_id=review_model.id,
        )
        if not author_capability.get("supported") or not reviewer_capability.get("supported"):
            raise ValueError("MODEL_STRUCTURED_OUTPUT_UNSUPPORTED: selected author or reviewer did not pass the v3 conformance suite")
        if not self.v3.workflow.resume(task_id):
            raise ValueError("The CAD task no longer has a recoverable retry checkpoint")
        self._autonomous_runs[task_id] = asyncio.create_task(
            self._consume_discarding(
                task_id,
                ModelIdentity(author_provider.id, author_model.id),
                ModelIdentity(review_provider.id, review_model.id),
            ),
            name=f"resume-autonomous-cad-v3-{task_id}",
        )
        return self.v3.repository.get_task_projection(task_id)

    async def stream(
        self,
        messages: list[ChatMessage],
        conversation_id: str | None,
        selected_task_id: str | None,
        provider_id: str | None = None,
        model_id: str | None = None,
        viewer_context: list[dict[str, Any]] | None = None,
    ) -> AsyncIterator[bytes]:
        del viewer_context
        latest_user = next((message for message in reversed(messages) if message.role == "user"), None)
        if latest_user is None or not text_from_message(latest_user):
            yield event("cad_error", {"stage": "request", "message": "A non-empty user request is required."})
            yield event("done", {})
            return
        request = text_from_message(latest_user)
        conversation = self.store.ensure_conversation(conversation_id)
        selected = str(selected_task_id or conversation.get("current_task_id") or "")
        current = self.v3.repository.get_task_projection(selected) if selected else None
        resumed_task_id = ""
        if current and str(current.get("lifecycle") or "") == "waiting_for_user":
            state = self.v3.repository.get_state(selected)
            if state is not None:
                terminal = self.v3.workflow.waiting_for_user_terminal(selected, state)
                fields = [
                    {
                        "path": f"/requirements/{str(item.get('draftId') or 'review')}",
                        "message": str(item.get("question") or item.get("reasonCode") or "Unresolved review item."),
                    }
                    for item in terminal.get("unresolved") or ()
                    if isinstance(item, dict)
                ]
                fields.extend({"path": "/requirements/review", "message": issue} for issue in terminal.get("issues") or ())
                if not self.v3.workflow.resume_with_user_clarification(selected, request, message_id=latest_user.id):
                    yield event("cad_error", {
                        "stage": "request",
                        "message": "This parked CAD task cannot apply the supplied clarification. " + str(terminal["message"]),
                        "fieldErrors": fields,
                        "taskId": selected,
                        "blockerType": terminal.get("blockerType"),
                        "userActionRequired": terminal.get("userActionRequired"),
                    })
                    yield event("done", {})
                    return
                resumed_task_id = selected
        try:
            author_provider, author_model = self.settings.resolve_model(provider_id, model_id)
            review_provider, review_model = self.settings.resolve_independent_review_model(author_provider, author_model)
        except ValueError as error:
            yield event("cad_error", {"stage": "configuration", "message": str(error)})
            yield event("done", {})
            return
        try:
            author_capability = await verify_model_capability(self.v3.repository, self.v3.workflow.runtime, self.v3.models, provider_id=author_provider.id, model_id=author_model.id)
            reviewer_capability = await verify_model_capability(self.v3.repository, self.v3.workflow.runtime, self.v3.models, provider_id=review_provider.id, model_id=review_model.id)
        except Exception as error:
            yield event("cad_error", {"stage": "configuration", "message": f"MODEL_STRUCTURED_OUTPUT_UNSUPPORTED: {str(error)[:500]}"})
            yield event("done", {})
            return
        if not author_capability.get("supported") or not reviewer_capability.get("supported"):
            yield event("cad_error", {"stage": "configuration", "message": "MODEL_STRUCTURED_OUTPUT_UNSUPPORTED: selected author or reviewer did not pass the v3 conformance suite."})
            yield event("done", {})
            return
        if current and str(current.get("lifecycle") or "") == "running":
            yield event("cad_error", {"stage": "request", "message": "该 CAD 任务正在生成，完成或失败前不能继续对话。"})
            yield event("done", {})
            return
        # A terminal task is immutable. A legacy task is never migrated: both
        # cases intentionally create a fresh v3 task.
        task_id = resumed_task_id or f"cad_{secrets.token_hex(6)}"
        if not resumed_task_id:
            try:
                source_blocks = self._task_source_blocks(conversation, request)
                self.v3.workflow.create_task(task_id, request, source_blocks=source_blocks)
            except ValueError as error:
                yield event("cad_error", {"stage": "request", "message": str(error)})
                yield event("done", {})
                return
        conversation = self.store.append_conversation_message(conversation["conversation_id"], latest_user.model_dump(), task_id)
        yield event("progress", {"taskId": task_id, "step": "task_started", "label": "Agent", "status": "running", "message": "已应用补充说明并恢复 CAD 任务。" if resumed_task_id else "CAD 任务已启动。" if _response_language(request) == "Chinese" else "CAD task started."})

        queue: asyncio.Queue[tuple[str, dict[str, Any]] | None] = asyncio.Queue()
        parts: list[dict[str, Any]] = []
        sequence = 0

        async def consume() -> None:
            nonlocal sequence

            async def dispatch_state_events() -> None:
                """Publish state notifications only through the outbox.

                The dispatcher preserves at-least-once semantics.  The SSE
                event ID derives from the durable outbox row, so reconnecting
                clients can safely de-duplicate a delivery replay.
                """
                nonlocal sequence
                for outbox_event in await self.v3.outbox.dispatch_pending(task_id=task_id):
                    sequence += 1
                    event_name = str(outbox_event.get("event") or "state_changed")
                    payload = {
                        "taskId": task_id,
                        "eventId": f"outbox_{outbox_event['event_id']}",
                        "sequence": sequence,
                        "timestamp": now_iso(),
                        "outboxEvent": event_name,
                        "message": event_name.replace("_", " "),
                    }
                    await queue.put(("progress", _visible_progress("state_changed", payload)))

            try:
                async for name, payload in self.v3.workflow.run(
                    task_id=task_id,
                    author=ModelIdentity(author_provider.id, author_model.id),
                    reviewer=ModelIdentity(review_provider.id, review_model.id),
                ):
                    sequence += 1
                    decorated = {**payload, "taskId": task_id, "eventId": str(payload.get("eventId") or f"{task_id}_{sequence}_{name}"), "sequence": sequence, "timestamp": now_iso()}
                    _upsert_part(parts, {"type": "data-cad-progress", "id": decorated["eventId"], "data": _visible_progress(name, decorated)})
                    if name == "task_terminal" and str(decorated.get("lifecycle") or "") == "failed":
                        _upsert_part(parts, {"type": "data-cad-error", "id": f"{decorated['eventId']}_error", "data": {
                            "stage": "generation",
                            "message": str(decorated.get("message") or "CAD autonomous generation failed."),
                            "tool": str(decorated.get("tool") or ""),
                            "fieldErrors": decorated.get("field_errors") if isinstance(decorated.get("field_errors"), list) else [],
                        }})
                    await queue.put((name, decorated))
                    await dispatch_state_events()
            except Exception as error:
                sequence += 1
                terminal = {"taskId": task_id, "lifecycle": "failed", "code": "FAILED_INTERNAL", "message": str(error)[:1000], "eventId": f"{task_id}_{sequence}_task_terminal", "sequence": sequence, "timestamp": now_iso(), "userActionRequired": False}
                _upsert_part(parts, {"type": "data-cad-progress", "id": terminal["eventId"], "data": _visible_progress("task_terminal", terminal)})
                _upsert_part(parts, {"type": "data-cad-error", "id": f"{terminal['eventId']}_error", "data": {"stage": "generation", "message": terminal["message"], "fieldErrors": []}})
                await queue.put(("task_terminal", terminal))
            finally:
                self.store.append_conversation_message(conversation["conversation_id"], {"id": f"assistant_{secrets.token_hex(8)}", "role": "assistant", "parts": parts}, task_id)
                self._autonomous_runs.pop(task_id, None)
                await queue.put(None)

        self._autonomous_runs[task_id] = asyncio.create_task(consume(), name=f"autonomous-cad-v3-{task_id}")
        while True:
            try:
                item = await asyncio.wait_for(queue.get(), timeout=15)
            except asyncio.TimeoutError:
                yield event("heartbeat", {"taskId": task_id, "timestamp": now_iso()})
                continue
            if item is None:
                break
            name, payload = item
            if name == "task_terminal" and str(payload.get("lifecycle") or "") == "failed":
                yield event("cad_error", {
                    "stage": "generation",
                    "message": str(payload.get("message") or "CAD autonomous generation failed."),
                    "tool": str(payload.get("tool") or ""),
                    "fieldErrors": payload.get("field_errors") if isinstance(payload.get("field_errors"), list) else [],
                })
            yield event(name, payload)
        yield event("done", {})

    def _task_source_blocks(self, conversation: dict[str, Any], request: str) -> list[dict[str, Any]]:
        """Freeze message paragraphs and attachment blocks before task creation."""
        blocks = [{"text": paragraph} for paragraph in re.split(r"\n\s*\n", request) if paragraph.strip()]
        conversation_id = str(conversation.get("conversation_id") or "")
        if not conversation_id:
            raise ValueError("Conversation has no identifier")
        for attachment in conversation.get("attachments") or ():
            if not isinstance(attachment, dict):
                continue
            if str(attachment.get("conversation_id") or "") != conversation_id:
                raise ValueError("Attachment does not belong to this conversation")
            attachment_id = str(attachment.get("id") or "")
            relative_path = str(attachment.get("path") or "")
            expected_digest = str(attachment.get("sha256") or "")
            if not attachment_id or not relative_path or not re.fullmatch(r"[a-f0-9]{64}", expected_digest):
                raise ValueError("Attachment metadata is incomplete")
            binary_path = self.store.conversation_attachment_path(conversation_id, relative_path)
            if not binary_path.is_file():
                raise ValueError(f"Attachment is missing: {attachment.get('name') or attachment_id}")
            if sha256(binary_path.read_bytes()).hexdigest() != expected_digest:
                raise ValueError(f"Attachment checksum mismatch: {attachment.get('name') or attachment_id}")
            kind = str(attachment.get("kind") or "")
            if kind == "document":
                extracted_path = str(attachment.get("extracted_path") or "")
                if not extracted_path:
                    raise ValueError(f"Attachment text is unavailable: {attachment.get('name') or attachment_id}")
                text_path = self.store.conversation_attachment_path(conversation_id, extracted_path)
                if not text_path.is_file():
                    raise ValueError(f"Attachment text is missing: {attachment.get('name') or attachment_id}")
                text = text_path.read_text(encoding="utf-8", errors="replace").strip()
            elif kind == "image":
                # The binary is integrity-checked above.  Do not claim that a
                # text-only author has interpreted visual content; the source
                # block is still a stable, reviewable attachment reference.
                text = (
                    f"Visual attachment {attachment.get('name') or attachment_id} "
                    f"(SHA-256 {expected_digest}, MIME {attachment.get('mime') or 'image/*'}). "
                    "It is a visual reference and requires explicit visual verification."
                )
            else:
                raise ValueError(f"Unsupported attachment kind: {kind or 'unknown'}")
            if not text:
                raise ValueError(f"Attachment source is empty: {attachment.get('name') or attachment_id}")
            blocks.append({
                "text": text,
                "attachment": {
                    "attachment_id": attachment_id,
                    "name": str(attachment.get("name") or attachment_id),
                    "kind": kind,
                    "mime": str(attachment.get("mime") or "application/octet-stream"),
                    "sha256": expected_digest,
                },
            })
        return blocks