from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from flower.common import ModelBase
from typing import List


class State(ModelBase):
    """State model representing a state in a stateflow diagram."""
    name = models.CharField(max_length=100, verbose_name='状态名称')
    # previous = models.ForeignKey('self', null=True, blank=True, on_delete=models.SET_NULL, verbose_name='上一级状态')
    description = models.CharField(max_length=200, blank=True, verbose_name='状态描述')

    def __str__(self):
        return self.name

    def add_additional_params(self, params: dict):
        """Add additional parameters to the state's data field."""
        if not self.data:
            self.data = {}
        self.data.update(params)
        self.save()

    def get_additional_params(self) -> dict:
        """Retrieve additional parameters from the state's data field."""
        return self.data if self.data else {}

    class Meta:
        verbose_name = '流程节点'
        verbose_name_plural = '流程节点'


class StateParameter(ModelBase):
    """StateParameter model representing parameters associated with a state."""
    state = models.ForeignKey(State, on_delete=models.PROTECT, related_name='parameters', verbose_name='关联参数')
    key = models.CharField(max_length=100, verbose_name='参数键')
    value = models.CharField(max_length=200, verbose_name='参数值')
    description = models.CharField(max_length=200, blank=True, verbose_name='参数描述')

    def __str__(self):
        return f"{self.state.name} - {self.key}"

    class Meta:
        verbose_name = '工艺参数'
        verbose_name_plural = '工艺参数'


class Process(ModelBase):
    """Process model representing a stateflow process template."""
    name = models.CharField(max_length=100, verbose_name='流程名称')
    state_nodes = models.ManyToManyField(
        State,
        through='ProcessNode',
        related_name='processes',
        verbose_name='节点列表',
    )
    description = models.TextField(blank=True, verbose_name='流程描述')

    def __str__(self):
        return self.name

    def replace_nodes(self, nodes: List[State]):
        """Replace all nodes with new ordered list."""
        # 清空现有节点后按照传入顺序重建
        self.process_nodes.all().delete()
        for order, node in enumerate(nodes):
            ProcessNode.objects.create(process=self, state=node, order=order)

    def get_nodes(self) -> List[State]:
        """Retrieve the list of state nodes as State instances."""
        process_nodes = self.process_nodes.select_related('state').order_by('order', 'id')
        return [item.state for item in process_nodes]

    class Meta:
        verbose_name = '流程编排'
        verbose_name_plural = '流程编排'


class ProcessNode(ModelBase):
    """Intermediate model describing ordered relation between Process and State."""
    process = models.ForeignKey(Process, on_delete=models.CASCADE, related_name='process_nodes', verbose_name='流程')
    state = models.ForeignKey(State, on_delete=models.PROTECT, related_name='state_process_nodes', verbose_name='节点')
    order = models.PositiveIntegerField(default=0, verbose_name='顺序')

    class Meta:
        verbose_name = '流程节点关联'
        verbose_name_plural = '流程节点关联'
        ordering = ['order', 'id']
        unique_together = ('process', 'order')

    def __str__(self) -> str:
        return f"{self.process.name} -> {self.state.name} ({self.order})"


class BusinessObject(ModelBase):
    """业务对象 - 代表流程的一个实例，通过日志跟踪进度"""
    name = models.CharField(max_length=100, verbose_name='业务对象名称')
    process = models.ForeignKey(Process, on_delete=models.PROTECT, related_name='business_objects', verbose_name='关联流程')
    description = models.TextField(blank=True, verbose_name='描述')
    
    # GenericForeignKey - 关联到任意模型（可选）
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE, null=True, blank=True, verbose_name='关联对象类型')
    object_id = models.PositiveIntegerField(null=True, blank=True, verbose_name='关联对象ID')
    content_object = GenericForeignKey('content_type', 'object_id')

    def __str__(self):
        return f"{self.name} ({self.process.name})"

    def get_current_state(self) -> 'State':
        """获取当前状态（通过services推导）"""
        from . import services
        return services.get_business_object_current_state(self)

    def get_completed_node_ids(self) -> List[int]:
        """获取已完成的节点ID列表"""
        from . import services
        return services.get_completed_node_ids(self)

    def get_current_parameters(self) -> List['StateParameter']:
        """获取当前状态的参数"""
        from . import services
        return services.get_current_state_parameters(self)

    def get_progress_percentage(self) -> float:
        """计算进度百分比"""
        from . import services
        return services.get_progress_percentage(self)

    def get_state_status(self, state: 'State') -> str:
        """获取指定状态的状态"""
        from . import services
        return services.get_business_object_state_status(self, state)

    def get_timeline(self) -> List[dict]:
        """获取状态时间线"""
        from . import services
        return services.get_business_object_state_timeline(self)

    class Meta:
        db_table = 'business_object'
        verbose_name = '业务对象'
        verbose_name_plural = '业务对象'


class StateFlowRecord(ModelBase):
    """状态流转记录"""
    business_object = models.ForeignKey(BusinessObject, on_delete=models.CASCADE, related_name='state_logs', verbose_name='业务对象')
    state = models.ForeignKey(State, on_delete=models.CASCADE, verbose_name='状态')
    completed_at = models.DateTimeField(auto_now_add=True, verbose_name='完成时间')
    completed_by = models.ForeignKey('auth.User', on_delete=models.SET_NULL, null=True, verbose_name='操作人')
    cancelled_at = models.DateTimeField(null=True, blank=True, verbose_name='撤销时间')
    is_cancelled = models.BooleanField(default=False, verbose_name='是否已撤销')
    
    class Meta:
        db_table = 'state_flow_record'
        verbose_name = '状态流转记录'
        verbose_name_plural = '状态流转记录'
        # 移除 unique_together 约束，允许同一状态多次记录（支持撤销后重新执行）
        ordering = ['completed_at']