from copy import deepcopy
from datetime import UTC, datetime

from app.domain.models import (
    CommandRequest,
    ProjectSnapshot,
    WorkflowCommand,
    WorkflowDefinition,
    WorkflowStage,
    WorkflowStageDefinition,
)


class WorkflowConflictError(RuntimeError):
    pass


class InvalidTransitionError(RuntimeError):
    pass


TRANSITIONS: dict[WorkflowStage, dict[WorkflowCommand, WorkflowStage]] = {
    WorkflowStage.UPLOADED: {
        WorkflowCommand.START_INGESTION: WorkflowStage.REGION_SELECTION,
    },
    WorkflowStage.REGION_SELECTION: {
        WorkflowCommand.SELECT_REGION: WorkflowStage.PLAN_REVIEW,
    },
    WorkflowStage.PLAN_REVIEW: {
        WorkflowCommand.CONFIRM_PLAN: WorkflowStage.BLOCKOUT,
    },
    WorkflowStage.BLOCKOUT: {
        WorkflowCommand.BUILD_BLOCKOUT: WorkflowStage.STYLE_BRIEF,
    },
    WorkflowStage.STYLE_BRIEF: {
        WorkflowCommand.SUBMIT_STYLE_BRIEF: WorkflowStage.DIRECTION_SELECTION,
    },
    WorkflowStage.DIRECTION_SELECTION: {
        WorkflowCommand.SELECT_DIRECTION: WorkflowStage.RENDER_REVIEW,
    },
    WorkflowStage.RENDER_REVIEW: {
        WorkflowCommand.REQUEST_RENDER: WorkflowStage.EDITING,
        WorkflowCommand.COMPLETE_PROJECT: WorkflowStage.COMPLETED,
    },
    WorkflowStage.EDITING: {
        WorkflowCommand.APPLY_EDIT: WorkflowStage.EDITING,
        WorkflowCommand.REQUEST_RENDER: WorkflowStage.EDITING,
        WorkflowCommand.COMPLETE_PROJECT: WorkflowStage.COMPLETED,
    },
    WorkflowStage.FAILED: {
        WorkflowCommand.RETRY: WorkflowStage.PLAN_REVIEW,
    },
    WorkflowStage.COMPLETED: {
        WorkflowCommand.APPLY_EDIT: WorkflowStage.EDITING,
    },
}


def available_commands(stage: WorkflowStage) -> list[WorkflowCommand]:
    return list(TRANSITIONS.get(stage, {}).keys())


def apply_command(project: ProjectSnapshot, request: CommandRequest) -> ProjectSnapshot:
    if request.expected_revision != project.revision:
        raise WorkflowConflictError(
            f"Expected revision {request.expected_revision}, current revision is {project.revision}."
        )

    target = TRANSITIONS.get(project.stage, {}).get(request.command)
    if target is None:
        raise InvalidTransitionError(
            f"Command '{request.command}' is not allowed while project is in '{project.stage}'."
        )

    updated = deepcopy(project)
    updated.last_stable_stage = project.stage
    updated.stage = target
    updated.revision += 1
    updated.updated_at = datetime.now(UTC)
    updated.failure_reason = None

    if request.command == WorkflowCommand.SELECT_REGION:
        updated.plan.selected_region_id = request.payload.get("region_id")
    elif request.command == WorkflowCommand.CONFIRM_PLAN:
        updated.plan.ceiling_height_mm = int(
            request.payload.get("ceiling_height_mm", updated.plan.ceiling_height_mm)
        )
    elif request.command == WorkflowCommand.SUBMIT_STYLE_BRIEF:
        for field in ("concept", "lighting", "forms", "density"):
            if field in request.payload:
                setattr(updated.style, field, request.payload[field])
        for field in ("keywords", "materials", "avoid", "locked_decisions"):
            if field in request.payload:
                setattr(updated.style, field, list(request.payload[field]))

    updated.available_commands = available_commands(updated.stage)
    return updated


def workflow_definition() -> WorkflowDefinition:
    labels = {
        WorkflowStage.UPLOADED: ("文件已上传", "验证文件并准备解析", False),
        WorkflowStage.REGION_SELECTION: ("选择户型", "从复杂图纸中选择目标平面区域", True),
        WorkflowStage.PLAN_REVIEW: ("确认结构", "检查墙、门窗、比例和保留家具", True),
        WorkflowStage.BLOCKOUT: ("生成白模", "建立空间骨架、家具占位和相机", False),
        WorkflowStage.STYLE_BRIEF: ("明确风格", "形成结构化 Style DNA", True),
        WorkflowStage.DIRECTION_SELECTION: ("选择方向", "比较并锁定主设计方向", True),
        WorkflowStage.RENDER_REVIEW: ("审阅效果", "检查空间忠实度与审美一致性", True),
        WorkflowStage.EDITING: ("多轮修改", "通过结构化操作局部修改", True),
        WorkflowStage.COMPLETED: ("方案完成", "导出概念方案与版本记录", False),
        WorkflowStage.FAILED: ("需要处理", "展示错误并从稳定阶段恢复", True),
    }
    return WorkflowDefinition(
        stages=[
            WorkflowStageDefinition(
                id=stage,
                label=labels[stage][0],
                purpose=labels[stage][1],
                human_confirmation=labels[stage][2],
            )
            for stage in WorkflowStage
        ],
        transitions={
            stage.value: [command.value for command in commands]
            for stage, commands in TRANSITIONS.items()
        },
    )