from datetime import datetime, timedelta

from sqlalchemy.orm import Session

from core_domain import ChatCompletionRequestContract, ChatMessageContract
from core_shared import JSONValue

from app.bootstrap.settings import AgentServiceSettings
from app.db.models import AgentDefinition, AgentRun, AgentVersion
from app.domain.repositories import (
    AgentDefinitionRepository,
    AgentRunRepository,
    AgentVersionRepository,
)
from app.infrastructure.model_gateway_client import ModelGatewayClient, ModelGatewayClientError
from app.schemas.agent import (
    AgentCreateRequest,
    AgentRunCreateRequest,
    AgentRunExecuteRequest,
    AgentRunStatusUpdateRequest,
    AgentStatusUpdateRequest,
    AgentVersionCreateRequest,
)


class AgentApplicationService:
    def __init__(
        self,
        *,
        agent_repository: AgentDefinitionRepository,
        agent_version_repository: AgentVersionRepository,
        agent_run_repository: AgentRunRepository,
        model_gateway_client: ModelGatewayClient | None = None,
    ) -> None:
        self.agent_repository = agent_repository
        self.agent_version_repository = agent_version_repository
        self.agent_run_repository = agent_run_repository
        self.model_gateway_client = model_gateway_client

    def create_agent(self, payload: AgentCreateRequest) -> AgentDefinition:
        return self.agent_repository.create(
            tenant_id=payload.tenant_id,
            code=payload.code,
            name=payload.name,
            description=payload.description,
            agent_type=payload.agent_type,
            owner_user_id=payload.owner_user_id,
            metadata_json=payload.metadata_json,
        )

    def list_agents(self, *, tenant_id: str) -> list[AgentDefinition]:
        return self.agent_repository.list_by_tenant(tenant_id=tenant_id)

    def update_agent_status(
        self,
        *,
        agent_id: str,
        payload: AgentStatusUpdateRequest,
    ) -> AgentDefinition | None:
        return self.agent_repository.update_status(
            tenant_id=payload.tenant_id,
            agent_id=agent_id,
            status=payload.status,
        )

    def create_agent_version(self, payload: AgentVersionCreateRequest) -> AgentVersion:
        agent = self.agent_repository.get_by_id(
            tenant_id=payload.tenant_id,
            agent_id=payload.agent_id,
        )
        if agent is None:
            raise ValueError(f"agent not found: {payload.agent_id}")

        return self.agent_version_repository.create(
            tenant_id=payload.tenant_id,
            agent_id=payload.agent_id,
            status=payload.status,
            role=payload.role,
            goal=payload.goal,
            system_prompt=payload.system_prompt,
            model_config_json=payload.model_config_data.model_dump(mode="json"),
            memory_policy_json=payload.memory_policy.model_dump(mode="json"),
            tool_refs_json=[item.model_dump(mode="json") for item in payload.tool_refs],
            skill_refs_json=[item.model_dump(mode="json") for item in payload.skill_refs],
        )

    def list_agent_versions(self, *, tenant_id: str, agent_id: str) -> list[AgentVersion]:
        return self.agent_version_repository.list_by_agent(tenant_id=tenant_id, agent_id=agent_id)

    def create_agent_run(self, payload: AgentRunCreateRequest) -> AgentRun:
        agent_version = self._resolve_agent_version(
            tenant_id=payload.tenant_id,
            agent_id=payload.agent_id,
            agent_version_id=payload.agent_version_id,
        )
        if agent_version is None:
            raise ValueError("published agent version not found")

        return self.agent_run_repository.create(
            tenant_id=payload.tenant_id,
            agent_id=payload.agent_id,
            agent_version_id=agent_version.id,
            session_id=payload.session_id,
            input_text=payload.input_text,
            input_json=payload.input_json,
        )

    def list_agent_runs(
        self,
        *,
        tenant_id: str,
        agent_id: str | None = None,
        session_id: str | None = None,
    ) -> list[AgentRun]:
        return self.agent_run_repository.list_by_scope(
            tenant_id=tenant_id,
            agent_id=agent_id,
            session_id=session_id,
        )

    def update_agent_run_status(
        self,
        *,
        agent_run_id: str,
        payload: AgentRunStatusUpdateRequest,
    ) -> AgentRun | None:
        entity = self.agent_run_repository.get_by_id(
            tenant_id=payload.tenant_id,
            agent_run_id=agent_run_id,
        )
        if entity is None:
            return None
        return self.agent_run_repository.update_status(
            agent_run_id=agent_run_id,
            status=payload.status,
            worker_key=payload.worker_key,
            output_text=payload.output_text,
            output_json=payload.output_json,
            error_code=payload.error_code,
            error_message=payload.error_message,
        )

    def execute_agent_run(
        self,
        *,
        agent_run_id: str,
        payload: AgentRunExecuteRequest,
    ) -> AgentRun | None:
        agent_run = self.agent_run_repository.get_by_id(
            tenant_id=payload.tenant_id,
            agent_run_id=agent_run_id,
        )
        if agent_run is None:
            return None

        agent_version = self.agent_version_repository.get_by_id(
            tenant_id=payload.tenant_id,
            agent_version_id=agent_run.agent_version_id,
        )
        if agent_version is None:
            return self.agent_run_repository.update_status(
                agent_run_id=agent_run.id,
                status="failed",
                worker_key=payload.worker_key,
                error_code="agent_version_missing",
                error_message=f"agent version not found: {agent_run.agent_version_id}",
            )

        self.agent_run_repository.update_status(
            agent_run_id=agent_run.id,
            status="running",
            worker_key=payload.worker_key,
        )

        messages = self._build_chat_messages(agent_run=agent_run, agent_version=agent_version)
        if payload.dry_run:
            return self.agent_run_repository.update_status(
                agent_run_id=agent_run.id,
                status="completed",
                worker_key=payload.worker_key,
                output_text=self._build_dry_run_output(
                    agent_run=agent_run,
                    agent_version=agent_version,
                ),
                output_json={
                    "dry_run": True,
                    "agent_version_id": agent_version.id,
                    "message_count": len(messages),
                    "messages": [message.model_dump(mode="json") for message in messages],
                },
            )

        if self.model_gateway_client is None:
            return self.agent_run_repository.update_status(
                agent_run_id=agent_run.id,
                status="failed",
                worker_key=payload.worker_key,
                error_code="model_gateway_missing",
                error_message="model gateway client is not configured",
            )

        try:
            response = self.model_gateway_client.create_chat_completion(
                ChatCompletionRequestContract(
                    model=self._read_optional_string(agent_version.model_config_json, "model"),
                    temperature=self._read_optional_float(
                        agent_version.model_config_json,
                        "temperature",
                    ),
                    max_tokens=self._read_optional_int(agent_version.model_config_json, "max_tokens"),
                    messages=messages,
                    metadata_json={
                        "tenant_id": agent_run.tenant_id,
                        "agent_id": agent_run.agent_id,
                        "agent_version_id": agent_version.id,
                        "agent_run_id": agent_run.id,
                    },
                )
            )
        except ModelGatewayClientError as exc:
            return self.agent_run_repository.update_status(
                agent_run_id=agent_run.id,
                status="failed",
                worker_key=payload.worker_key,
                error_code="model_gateway_error",
                error_message=str(exc),
            )

        return self.agent_run_repository.update_status(
            agent_run_id=agent_run.id,
            status="completed",
            worker_key=payload.worker_key,
            output_text=response.content,
            output_json={
                "dry_run": False,
                "agent_version_id": agent_version.id,
                "model": response.model,
                "finish_reason": response.finish_reason,
                "usage_json": response.usage_json,
                "raw_response_json": response.raw_response_json,
            },
        )

    def execute_next_claimed_agent_run(
        self,
        *,
        worker_key: str,
        lease_seconds: int,
        dry_run: bool,
    ) -> tuple[AgentRun, int] | None:
        released_lease_count = self.agent_run_repository.release_expired_leases(
            now_time=datetime.utcnow(),
        )
        claimed_agent_run = self.agent_run_repository.claim_next_queued(
            worker_key=worker_key,
            lease_expire_time=datetime.utcnow() + timedelta(seconds=lease_seconds),
        )
        if claimed_agent_run is None:
            return None

        result = self.execute_agent_run(
            agent_run_id=claimed_agent_run.id,
            payload=AgentRunExecuteRequest(
                tenant_id=claimed_agent_run.tenant_id,
                worker_key=worker_key,
                dry_run=dry_run,
            ),
        )
        if result is None:
            return None
        return result, released_lease_count

    def _resolve_agent_version(
        self,
        *,
        tenant_id: str,
        agent_id: str,
        agent_version_id: str | None,
    ) -> AgentVersion | None:
        if agent_version_id is not None:
            return self.agent_version_repository.get_by_id(
                tenant_id=tenant_id,
                agent_version_id=agent_version_id,
            )
        return self.agent_version_repository.get_latest_published(
            tenant_id=tenant_id,
            agent_id=agent_id,
        )

    def _build_chat_messages(
        self,
        *,
        agent_run: AgentRun,
        agent_version: AgentVersion,
    ) -> list[ChatMessageContract]:
        messages = [
            ChatMessageContract(role="system", content=agent_version.system_prompt),
        ]
        if agent_version.goal:
            messages.append(ChatMessageContract(role="system", content=f"Goal: {agent_version.goal}"))
        if agent_run.input_text:
            messages.append(ChatMessageContract(role="user", content=agent_run.input_text))
        if agent_run.input_json:
            messages.append(
                ChatMessageContract(
                    role="user",
                    content=f"Structured input: {agent_run.input_json}",
                )
            )
        return messages

    def _build_dry_run_output(self, *, agent_run: AgentRun, agent_version: AgentVersion) -> str:
        input_preview = agent_run.input_text or str(agent_run.input_json or {})
        return (
            f"[dry-run] Agent role={agent_version.role} "
            f"version={agent_version.version_no} received: {input_preview}"
        )

    def _read_optional_string(self, payload: dict[str, JSONValue], key: str) -> str | None:
        value = payload.get(key)
        if isinstance(value, str) and value:
            return value
        return None

    def _read_optional_float(self, payload: dict[str, JSONValue], key: str) -> float | None:
        value = payload.get(key)
        if isinstance(value, (int, float)) and not isinstance(value, bool):
            return float(value)
        return None

    def _read_optional_int(self, payload: dict[str, JSONValue], key: str) -> int | None:
        value = payload.get(key)
        if isinstance(value, int) and not isinstance(value, bool):
            return value
        return None


def build_agent_application_service(
    *,
    db: Session,
    settings: AgentServiceSettings,
) -> AgentApplicationService:
    return AgentApplicationService(
        agent_repository=AgentDefinitionRepository(db),
        agent_version_repository=AgentVersionRepository(db),
        agent_run_repository=AgentRunRepository(db),
        model_gateway_client=ModelGatewayClient(
            base_url=settings.model_gateway_service_url,
            timeout_seconds=settings.model_gateway_timeout_seconds,
        ),
    )