from django.db import models
from django.utils import timezone

class AppSetting(models.Model):
    app_name = models.CharField(max_length=100, default="DN-WRS", verbose_name="Nama Aplikasi")
    app_description = models.TextField(blank=True, verbose_name="Deskripsi Aplikasi")
    app_address = models.TextField(blank=True, verbose_name="Alamat")
    app_phone = models.CharField(max_length=20, blank=True, verbose_name="Nomor Telepon")
    app_email = models.EmailField(blank=True, verbose_name="Email")
    
    def __str__(self):
        return self.app_name

    class Meta:
        verbose_name = "Pengaturan Aplikasi"
        verbose_name_plural = "Pengaturan Aplikasi"

class Category(models.Model):
    name = models.CharField(max_length=100, verbose_name="Nama Kategori")
    description = models.TextField(blank=True, verbose_name="Deskripsi")

    def __str__(self):
        return self.name

    class Meta:
        verbose_name_plural = "Kategori"
        verbose_name = "Kategori"

class Supplier(models.Model):
    name = models.CharField(max_length=255, verbose_name="Nama Supplier")
    contact_person = models.CharField(max_length=100, blank=True, verbose_name="Kontak Person")
    phone = models.CharField(max_length=20, blank=True, verbose_name="Telepon")
    address = models.TextField(blank=True, verbose_name="Alamat")

    def __str__(self):
        return self.name

    class Meta:
        verbose_name_plural = "Supplier"
        verbose_name = "Supplier"

class Medicine(models.Model):
    UNIT_CHOICES = [
        ('Tablet', 'Tablet'),
        ('Kapsul', 'Kapsul'),
        ('Botol', 'Botol'),
        ('Strip', 'Strip'),
        ('Pcs', 'Pcs'),
        ('Box', 'Box'),
    ]

    name = models.CharField(max_length=255, verbose_name="Nama Barang")
    category = models.ForeignKey(Category, on_delete=models.CASCADE, related_name='medicines', verbose_name="Kategori")
    sku = models.CharField(max_length=50, unique=True, verbose_name="SKU/Kode")
    unit = models.CharField(max_length=20, choices=UNIT_CHOICES, default='Tablet', verbose_name="Satuan")
    min_stock = models.IntegerField(default=10, verbose_name="Stok Minimal")
    main_supplier = models.ForeignKey(Supplier, on_delete=models.SET_NULL, null=True, blank=True, related_name='primary_medicines', verbose_name="Supplier Utama")
    alternative_supplier = models.ForeignKey(Supplier, on_delete=models.SET_NULL, null=True, blank=True, related_name='alternative_medicines', verbose_name="Supplier Alternatif")
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return self.name

    @property
    def total_stock(self):
        return sum(batch.quantity for batch in self.batches.all())

    @property
    def status(self):
        total = self.total_stock
        if total <= 0:
            return "Habis"
        if total <= self.min_stock:
            return "Stok Menipis"
        return "Tersedia"

    class Meta:
        verbose_name_plural = "Barang/Obat"
        verbose_name = "Barang/Obat"

class Faktur(models.Model):
    FAKTUR_TYPE_CHOICES = [
        ('MASUK', 'Faktur Masuk (Supplier)'),
        ('KELUAR', 'Faktur Keluar'),
    ]
    faktur_number = models.CharField(max_length=100, unique=True, verbose_name="Nomor Faktur")
    supplier = models.ForeignKey(Supplier, on_delete=models.SET_NULL, null=True, blank=True, verbose_name="Supplier")
    date = models.DateField(default=timezone.now, verbose_name="Tanggal")
    faktur_type = models.CharField(max_length=10, choices=FAKTUR_TYPE_CHOICES, default='MASUK', verbose_name="Tipe Faktur")
    notes = models.TextField(blank=True, verbose_name="Catatan")
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.faktur_number

    class Meta:
        verbose_name_plural = "Faktur"
        verbose_name = "Faktur"

class Batch(models.Model):
    medicine = models.ForeignKey(Medicine, on_delete=models.CASCADE, related_name='batches', verbose_name="Barang")
    faktur = models.ForeignKey(Faktur, on_delete=models.SET_NULL, null=True, blank=True, related_name='batches', verbose_name="Faktur")
    batch_number = models.CharField(max_length=100, verbose_name="Nomor Batch/Lot")
    expiry_date = models.DateField(verbose_name="Tanggal Kadaluarsa")
    quantity = models.IntegerField(default=0, verbose_name="Jumlah Stok")
    buying_price = models.DecimalField(max_digits=12, decimal_places=2, verbose_name="Harga Beli")
    selling_price = models.DecimalField(max_digits=12, decimal_places=2, verbose_name="Harga Jual")
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"{self.medicine.name} - {self.batch_number}"

    @property
    def is_expired(self):
        return self.expiry_date <= timezone.now().date()

    @property
    def is_near_expiry(self):
        today = timezone.now().date()
        diff = self.expiry_date - today
        return 0 < diff.days <= 90 # 3 months

    class Meta:
        verbose_name_plural = "Batch Barang"
        verbose_name = "Batch Barang"

class StockTransaction(models.Model):
    TRANSACTION_TYPES = [
        ('IN', 'Barang Masuk'),
        ('OUT', 'Barang Keluar'),
        ('ADJ', 'Penyesuaian'),
    ]

    medicine = models.ForeignKey(Medicine, on_delete=models.CASCADE, verbose_name="Barang")
    batch = models.ForeignKey(Batch, on_delete=models.SET_NULL, null=True, blank=True, related_name='transactions', verbose_name="Batch")
    faktur = models.ForeignKey(Faktur, on_delete=models.SET_NULL, null=True, blank=True, related_name='transactions', verbose_name="Faktur")
    transaction_type = models.CharField(max_length=3, choices=TRANSACTION_TYPES, verbose_name="Tipe Transaksi")
    quantity = models.IntegerField(verbose_name="Jumlah")
    note = models.TextField(blank=True, verbose_name="Keterangan")
    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Waktu")

    def __str__(self):
        return f"{self.get_transaction_type_display()} - {self.medicine.name} ({self.quantity})"

    class Meta:
        verbose_name_plural = "Transaksi Stok"
        verbose_name = "Transaksi Stok"