from django.db import models

from core.enums import (
    PermissionChangeAction,
    PermissionChangeTargetType,
    PermissionDataScopeType,
    PermissionOverrideMode,
)
from core.models.base import TimeStampedModel, UUIDPrimaryKeyModel


class StaffRole(UUIDPrimaryKeyModel):
    staff = models.ForeignKey(
        "org.Staff",
        on_delete=models.CASCADE,
        related_name="staff_roles",
    )
    role = models.ForeignKey(
        "fonrey_permission.Role",
        on_delete=models.PROTECT,
        related_name="staff_links",
    )
    is_primary = models.BooleanField(default=False)
    assigned_at = models.DateTimeField(auto_now_add=True)
    assigned_by = models.ForeignKey(
        "org.Staff",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="staff_role_assignments_made",
    )
    valid_from = models.DateField(null=True, blank=True)
    valid_until = models.DateField(null=True, blank=True)

    class Meta:
        db_table = "staff_roles"
        verbose_name = "员工角色"
        verbose_name_plural = "员工角色"
        constraints = [
            models.UniqueConstraint(
                fields=["staff", "role"],
                name="uq_staff_roles",
            ),
            models.UniqueConstraint(
                fields=["staff"],
                condition=models.Q(is_primary=True),
                name="uq_staff_roles_primary",
            ),
        ]
        indexes = [
            models.Index(fields=["role"], name="idx_staff_roles_role"),
        ]

    def __str__(self) -> str:
        marker = " [primary]" if self.is_primary else ""
        return f"{self.staff_id} → {self.role_id}{marker}"


class StaffPermissionOverride(UUIDPrimaryKeyModel):
    staff = models.ForeignKey(
        "org.Staff",
        on_delete=models.CASCADE,
        related_name="permission_overrides",
    )
    permission_def = models.ForeignKey(
        "fonrey_permission.PermissionDef",
        on_delete=models.PROTECT,
        related_name="staff_overrides",
    )
    value = models.JSONField()
    override_mode = models.CharField(
        max_length=10,
        choices=PermissionOverrideMode.choices,
        default=PermissionOverrideMode.REPLACE,
    )
    reason = models.TextField(blank=True, default="")
    modified_by = models.ForeignKey(
        "org.Staff",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="staff_overrides_modified",
    )
    modified_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "staff_permission_overrides"
        verbose_name = "个人权限覆盖"
        verbose_name_plural = "个人权限覆盖"
        constraints = [
            models.UniqueConstraint(
                fields=["staff", "permission_def"],
                name="uq_staff_overrides",
            ),
        ]
        indexes = [
            models.Index(fields=["staff"], name="idx_staff_overrides_staff"),
        ]


class StaffDataScope(UUIDPrimaryKeyModel):
    staff = models.ForeignKey(
        "org.Staff",
        on_delete=models.CASCADE,
        related_name="data_scopes",
    )
    scope_type = models.CharField(
        max_length=20,
        choices=PermissionDataScopeType.choices,
    )
    org_unit = models.ForeignKey(
        "org.OrgUnit",
        null=True,
        blank=True,
        on_delete=models.PROTECT,
        related_name="data_scope_grants",
    )
    is_readable = models.BooleanField(default=True)
    is_writable = models.BooleanField(default=False)
    granted_by = models.ForeignKey(
        "org.Staff",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="data_scopes_granted",
    )
    granted_at = models.DateTimeField(auto_now_add=True)
    expires_at = models.DateTimeField(null=True, blank=True)
    reason = models.TextField(blank=True, default="")

    class Meta:
        db_table = "staff_data_scopes"
        verbose_name = "员工数据范围"
        verbose_name_plural = "员工数据范围"
        indexes = [
            models.Index(fields=["staff"], name="idx_data_scopes_staff"),
            models.Index(fields=["org_unit"], name="idx_data_scopes_org"),
            models.Index(
                fields=["expires_at"],
                name="idx_data_scopes_expires",
                condition=models.Q(expires_at__isnull=False),
            ),
        ]


class PermissionChangeLog(UUIDPrimaryKeyModel):
    target_type = models.CharField(
        max_length=30,
        choices=PermissionChangeTargetType.choices,
    )
    target_id = models.UUIDField()
    staff = models.ForeignKey(
        "org.Staff",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="permission_change_logs_affecting",
    )
    role = models.ForeignKey(
        "fonrey_permission.Role",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="change_logs",
    )
    permission_code = models.CharField(max_length=150, blank=True, default="")
    action = models.CharField(max_length=20, choices=PermissionChangeAction.choices)
    old_value = models.JSONField(null=True, blank=True)
    new_value = models.JSONField(null=True, blank=True)
    operator = models.ForeignKey(
        "org.Staff",
        on_delete=models.PROTECT,
        related_name="permission_changes_operated",
    )
    operator_ip = models.GenericIPAddressField(null=True, blank=True)
    user_agent = models.TextField(blank=True, default="")
    reason = models.TextField(blank=True, default="")
    operated_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "permission_change_logs"
        verbose_name = "权限变更流水"
        verbose_name_plural = "权限变更流水"
        ordering = ["-operated_at"]
        indexes = [
            models.Index(
                fields=["staff", "-operated_at"],
                name="idx_perm_log_staff",
                condition=models.Q(staff__isnull=False),
            ),
            models.Index(
                fields=["role", "-operated_at"],
                name="idx_perm_log_role",
                condition=models.Q(role__isnull=False),
            ),
            models.Index(
                fields=["target_type", "target_id", "-operated_at"],
                name="idx_perm_log_target",
            ),
            models.Index(
                fields=["operator", "-operated_at"],
                name="idx_perm_log_operator",
            ),
            models.Index(fields=["-operated_at"], name="idx_perm_log_time"),
        ]

    def delete(self, *args, **kwargs):
        raise NotImplementedError("PermissionChangeLog is append-only and cannot be deleted.")