"""Workflow routes — CRUD, instance lifecycle, advance/cancel."""

from __future__ import annotations

import uuid

from fastapi import APIRouter, Depends, HTTPException, Query, Request, Response, status
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.db import get_db
from app.deps import require_permission
from app.schemas.workflow import AdvanceRequest, InstanceCreate, WorkflowCreate, WorkflowUpdate
from app.services import workflow_service

router = APIRouter(prefix="/api/v1/workflows", tags=["workflows"])


# ─── Workflow CRUD ───


@router.get("")
async def list_workflows(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    is_active: bool | None = Query(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """List workflows with pagination."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        return await workflow_service.list_workflows(
            db,
            tenant_id,
            page=page,
            page_size=page_size,
            is_active=is_active,
            user_id=user_id,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e


@router.post("", status_code=status.HTTP_201_CREATED)
async def create_workflow(
    body: WorkflowCreate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Create a new workflow definition. Requires write permission."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    data = body.model_dump()
    try:
        return await workflow_service.create_workflow(db, tenant_id, user_id, data)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e


@router.get("/instances")
async def list_instances(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    status: str | None = Query(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """List workflow instances with optional status filter."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        return await workflow_service.list_instances(
            db,
            tenant_id,
            page=page,
            page_size=page_size,
            status_filter=status,
            user_id=user_id,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e


@router.get("/{workflow_id}")
async def get_workflow(
    workflow_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """Get a single workflow by ID."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        result = await workflow_service.get_workflow(db, tenant_id, workflow_id, user_id=user_id, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.patch("/{workflow_id}")
async def update_workflow(
    workflow_id: str,
    body: WorkflowUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Update a workflow definition."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    data = body.model_dump(exclude_unset=True)
    try:
        result = await workflow_service.update_workflow(db, tenant_id, user_id, workflow_id, data, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.delete("/{workflow_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_workflow(
    workflow_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Delete a workflow definition."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        deleted = await workflow_service.delete_workflow(db, tenant_id, user_id, workflow_id, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if not deleted:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return Response(status_code=status.HTTP_204_NO_CONTENT)


# ─── Instance endpoints ───


@router.post("/{workflow_id}/instances", status_code=status.HTTP_201_CREATED)
async def create_instance(
    workflow_id: str,
    body: InstanceCreate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Create a new workflow instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        result = await workflow_service.create_instance(
            db,
            tenant_id,
            user_id,
            workflow_id=workflow_id,
            context=body.context,
            timeout_hours=body.timeout_hours,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.get("/instances/{instance_id}")
async def get_instance(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """Get a workflow instance with step history."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        result = await workflow_service.get_instance(db, tenant_id, instance_id, user_id=user_id, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    return result


@router.post("/instances/{instance_id}/advance")
async def advance_instance(
    instance_id: str,
    body: AdvanceRequest,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Advance or reject a workflow instance step.

    Body decision: "approve" or "reject".
    Returns 200 with updated instance.
    """
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        result = await workflow_service.advance_instance(
            db,
            tenant_id,
            user_id,
            instance_id=instance_id,
            decision=body.decision,
            comment=body.comment,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    if "error" in result:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"detail": result["error"], "code": "invalid_state"},
        )
    return result


@router.post("/instances/{instance_id}/cancel")
async def cancel_instance(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Cancel a workflow instance. Returns 200 with cancelled instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    try:
        result = await workflow_service.cancel_instance(
            db,
            tenant_id,
            user_id,
            instance_id=instance_id,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    if "error" in result:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"detail": result["error"], "code": "invalid_state"},
        )
    return result


# ─── G-RUN: Resume waiting workflow instance ──────────────────────────────────


@router.post("/instances/{instance_id}/resume")
async def resume_instance(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Resume a waiting workflow instance (e.g. after wait timer expired)."""
    tenant_id = uuid.UUID(current_user["tenant_id"])

    from app.workflows.engine import WorkflowEngine
    from app.models.workflow import WorkflowInstance
    from sqlalchemy import select

    result = await db.execute(
        select(WorkflowInstance).where(
            WorkflowInstance.id == uuid.UUID(instance_id),
            WorkflowInstance.tenant_id == tenant_id,
            WorkflowInstance.deleted_at.is_(None),
        )
    )
    instance = result.scalar_one_or_none()
    if instance is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    if instance.status != "waiting":
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"detail": "Instance is not waiting", "code": "invalid_state"},
        )

    engine = WorkflowEngine(db, tenant_id)
    return await engine.resume(instance)


# ─── G-MAN: Manual trigger — start workflow from UI button ────────────────────


@router.post("/{workflow_id}/trigger", status_code=status.HTTP_201_CREATED)
async def manual_trigger(
    workflow_id: str,
    request: Request,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Manually trigger a workflow — starts a new instance with optional context."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    try:
        body = await request.json()
    except Exception:
        body = {}

    result = await workflow_service.create_instance(
        db,
        tenant_id,
        user_id,
        workflow_id=workflow_id,
        context=body,
    )
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


# ─── G-WEB: Incoming webhook trigger ──────────────────────────────────────────


@router.post("/webhook/{token}", status_code=status.HTTP_200_OK)
async def webhook_trigger(
    token: str,
    request: Request,
    db: AsyncSession = Depends(get_db),
):
    """Incoming webhook trigger — starts a workflow via secure token."""
    from app.models.webhook import Webhook
    from sqlalchemy import select

    result = await db.execute(
        select(Webhook).where(
            Webhook.token == token,
            Webhook.is_active.is_(True),
        )
    )
    webhook = result.scalar_one_or_none()
    if webhook is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Webhook not found", "code": "not_found"},
        )

    try:
        payload = await request.json()
    except Exception:
        payload = {}

    result = await workflow_service.create_instance(
        db,
        webhook.tenant_id,
        None,
        workflow_id=str(webhook.workflow_id) if hasattr(webhook, "workflow_id") else str(webhook.entity_id),
        context={"webhook_payload": payload, "webhook_token": token},
    )
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return {"status": "triggered", "instance": result}


# ─── G-LOG: Step history for a workflow instance ─────────────────────────────


@router.get("/instances/{instance_id}/history")
async def get_instance_history(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """Get step history for a workflow instance (execution log)."""
    tenant_id = uuid.UUID(current_user["tenant_id"])

    from app.models.workflow import WorkflowStepHistory
    from sqlalchemy import select

    result = await db.execute(
        select(WorkflowStepHistory)
        .where(
            WorkflowStepHistory.tenant_id == tenant_id,
            WorkflowStepHistory.instance_id == uuid.UUID(instance_id),
        )
        .order_by(WorkflowStepHistory.created_at.asc())
    )
    history = result.scalars().all()
    return {
        "items": [
            {
                "id": str(h.id),
                "step_index": h.step_index,
                "step_type": h.step_type,
                "action": h.action,
                "actor_id": str(h.actor_id) if h.actor_id else None,
                "details": h.details,
                "created_at": h.created_at.isoformat() if h.created_at else None,
            }
            for h in history
        ],
        "total": len(history),
    }


# ─── G-APPROVAL: Approval step using central ApprovalRequest ─────────────────


@router.post("/instances/{instance_id}/approve")
async def approve_workflow_step(
    instance_id: str,
    request: Request,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Approve the current approval step of a workflow instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    try:
        body = await request.json()
    except Exception:
        body = {}
    comment = body.get("comment", "")

    from app.core.approval import create_approval_request, decide_approval
    from app.models.workflow import WorkflowInstance
    from sqlalchemy import select

    result = await db.execute(
        select(WorkflowInstance).where(
            WorkflowInstance.id == uuid.UUID(instance_id),
            WorkflowInstance.tenant_id == tenant_id,
            WorkflowInstance.deleted_at.is_(None),
        )
    )
    instance = result.scalar_one_or_none()
    if instance is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )

    approval = await create_approval_request(
        db=db,
        tenant_id=tenant_id,
        entity_type="workflow_instance",
        entity_id=uuid.UUID(instance_id),
        action="workflow_step_approval",
        requested_by=user_id,
        requested_by_type="user",
    )
    await decide_approval(
        db=db,
        approval_id=approval["id"],
        decision="approved",
        decided_by=user_id,
        comment=comment,
    )

    return await workflow_service.advance_instance(
        db,
        tenant_id,
        user_id,
        instance_id=instance_id,
        decision="approved",
        comment=comment,
        is_system_admin=current_user.get("is_system_admin", False),
    )


@router.post("/instances/{instance_id}/reject")
async def reject_workflow_step(
    instance_id: str,
    request: Request,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Reject the current approval step of a workflow instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    try:
        body = await request.json()
    except Exception:
        body = {}
    comment = body.get("comment", "")

    from app.core.approval import create_approval_request, decide_approval
    from app.models.workflow import WorkflowInstance
    from sqlalchemy import select

    result = await db.execute(
        select(WorkflowInstance).where(
            WorkflowInstance.id == uuid.UUID(instance_id),
            WorkflowInstance.tenant_id == tenant_id,
            WorkflowInstance.deleted_at.is_(None),
        )
    )
    instance = result.scalar_one_or_none()
    if instance is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )

    approval = await create_approval_request(
        db=db,
        tenant_id=tenant_id,
        entity_type="workflow_instance",
        entity_id=uuid.UUID(instance_id),
        action="workflow_step_approval",
        requested_by=user_id,
        requested_by_type="user",
    )
    await decide_approval(
        db=db,
        approval_id=approval["id"],
        decision="rejected",
        decided_by=user_id,
        comment=comment,
    )

    return await workflow_service.cancel_instance(
        db,
        tenant_id,
        user_id,
        instance_id=instance_id,
        is_system_admin=current_user.get("is_system_admin", False),
    )


# ─── G-UI-TEMPL: Template Gallery ─────────────────────────────────────────────


WORKFLOW_TEMPLATES = [
    {
        "id": "welcome_email",
        "name": "Welcome Email",
        "description": "Send a welcome email when a new contact is created",
        "trigger_event": "contact.after_create",
        "steps": [
            {"name": "Wait 1 hour", "type": "wait", "config": {"duration_seconds": 3600}},
            {"name": "Send Welcome", "type": "mail", "config": {
                "to": "{{context.email}}",
                "subject": "Welcome to our service!",
                "body": "Hello {{context.name}},\n\nWelcome aboard! We're excited to have you.\n\nBest regards,\nThe Team",
            }},
        ],
    },
    {
        "id": "contact_followup",
        "name": "Contact Follow-Up",
        "description": "Create a follow-up task 3 days after contact creation",
        "trigger_event": "contact.after_create",
        "steps": [
            {"name": "Wait 3 days", "type": "wait", "config": {"duration_seconds": 259200}},
            {"name": "Create Follow-Up Task", "type": "crm", "config": {
                "action": "create_contact",
                "data": {"title": "Follow up with {{context.name}}", "priority": "medium"},
            }},
            {"name": "Notify Owner", "type": "notification", "config": {
                "title": "Follow-up reminder",
                "body": "Time to follow up with {{context.name}}",
            }},
        ],
    },
    {
        "id": "approval_chain",
        "name": "Approval Chain",
        "description": "Two-step approval: manager approves, then sends notification",
        "trigger_event": "manual",
        "steps": [
            {"name": "Manager Approval", "type": "approval", "config": {}},
            {"name": "Send Result", "type": "mail", "config": {
                "to": "{{context.initiator_email}}",
                "subject": "Your request has been approved",
                "body": "Your request has been approved by management.",
            }},
            {"name": "Log Completion", "type": "event", "config": {
                "event_name": "approval_chain.completed",
                "payload": {},
            }},
        ],
    },
]


@router.get("/templates")
async def list_workflow_templates(
    current_user: dict = Depends(require_permission("workflows:read")),
):
    """List available workflow templates (G-UI-TEMPL)."""
    return {"items": WORKFLOW_TEMPLATES, "total": len(WORKFLOW_TEMPLATES)}


@router.post("/templates/{template_id}/instantiate", status_code=status.HTTP_201_CREATED)
async def instantiate_template(
    template_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("workflows:write")),
):
    """Instantiate a workflow template — creates a workflow from the template."""
    template = next((t for t in WORKFLOW_TEMPLATES if t["id"] == template_id), None)
    if template is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Template not found", "code": "not_found"},
        )

    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    data = {
        "name": template["name"],
        "description": template["description"],
        "trigger_event": template["trigger_event"],
        "steps": template["steps"],
        "is_active": True,
    }
    return await workflow_service.create_workflow(db, tenant_id, user_id, data)