from django.core.exceptions import ValidationError
from django.core.validators import MinValueValidator, RegexValidator
from django.db import models, transaction


class DownloadRelease(models.Model):
    class Platform(models.TextChoices):
        WINDOWS = "windows", "Windows"
        MACOS = "macos", "macOS"
        LINUX = "linux", "Linux"

    platform = models.CharField("平台", max_length=32, choices=Platform.choices)
    version = models.CharField("版本", max_length=64)
    file = models.FileField("安装包文件", upload_to="downloads/", blank=True)
    external_url = models.URLField("外部下载地址", blank=True)
    size_bytes = models.PositiveBigIntegerField(
        "文件大小字节数",
        null=True,
        blank=True,
        validators=[MinValueValidator(1)],
        help_text="客户端下载文件大小，单位字节；桌面端用于下载后校验。",
    )
    sha256 = models.CharField(
        "SHA256",
        max_length=64,
        blank=True,
        validators=[
            RegexValidator(
                regex=r"^[A-Fa-f0-9]{64}$",
                message="SHA256 必须是 64 位十六进制字符。",
            )
        ],
    )
    is_current = models.BooleanField("当前版本", default=False)
    force_update = models.BooleanField("强制更新", default=False)
    release_notes = models.TextField("发布说明", blank=True)
    created_at = models.DateTimeField("创建时间", auto_now_add=True)
    updated_at = models.DateTimeField("更新时间", auto_now=True)

    class Meta:
        db_table = "download_release"
        verbose_name = "客户端下载版本"
        verbose_name_plural = "客户端下载版本"
        ordering = ("platform", "-is_current", "-created_at", "-id")
        indexes = [
            models.Index(
                fields=("platform", "is_current"),
                name="dl_platform_current_idx",
            ),
        ]

    def __str__(self):
        return f"{self.get_platform_display()} {self.version}"

    @property
    def download_url(self) -> str:
        if self.external_url:
            return self.external_url
        if self.file:
            return self.file.url
        return ""

    @property
    def has_download(self) -> bool:
        return bool(self.download_url)

    def clean(self):
        super().clean()
        if not self.file and not self.external_url:
            raise ValidationError("安装包文件和外部下载地址至少填写一个。")

    def save(self, *args, **kwargs):
        with transaction.atomic():
            super().save(*args, **kwargs)
            if self.is_current:
                type(self).objects.filter(
                    platform=self.platform,
                    is_current=True,
                ).exclude(pk=self.pk).update(is_current=False)


class ImportTemplate(models.Model):
    name = models.CharField("模板名称", max_length=128)
    file = models.FileField("模板文件", upload_to="import_templates/", blank=True)
    external_url = models.URLField("外部下载地址", blank=True)
    sha256 = models.CharField(
        "SHA256",
        max_length=64,
        blank=True,
        validators=[
            RegexValidator(
                regex=r"^[A-Fa-f0-9]{64}$",
                message="SHA256 必须是 64 位十六进制字符。",
            )
        ],
    )
    is_current = models.BooleanField("当前模板", default=False)
    notes = models.TextField("说明", blank=True)
    created_at = models.DateTimeField("创建时间", auto_now_add=True)
    updated_at = models.DateTimeField("更新时间", auto_now=True)

    class Meta:
        db_table = "import_template"
        verbose_name = "导入模板"
        verbose_name_plural = "导入模板"
        ordering = ("-is_current", "-created_at", "-id")
        indexes = [
            models.Index(
                fields=("is_current",),
                name="it_current_idx",
            ),
        ]

    def __str__(self):
        return self.name

    @property
    def download_url(self) -> str:
        if self.external_url:
            return self.external_url
        if self.file:
            return self.file.url
        return ""

    @property
    def has_download(self) -> bool:
        return bool(self.download_url)

    def clean(self):
        super().clean()
        if not self.file and not self.external_url:
            raise ValidationError("模板文件和外部下载地址至少填写一个。")

    def save(self, *args, **kwargs):
        with transaction.atomic():
            super().save(*args, **kwargs)
            if self.is_current:
                type(self).objects.filter(is_current=True).exclude(pk=self.pk).update(
                    is_current=False
                )