from django.db import models


class Fertilizer(models.Model):
    name = models.CharField(max_length=100, unique=True, verbose_name='肥料名')
    maker = models.CharField(max_length=100, blank=True, null=True, verbose_name='メーカー')
    capacity_kg = models.DecimalField(
        max_digits=8, decimal_places=3, blank=True, null=True, verbose_name='1袋重量(kg)'
    )
    nitrogen_pct = models.DecimalField(
        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='窒素含有率(%)'
    )
    phosphorus_pct = models.DecimalField(
        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='リン酸含有率(%)'
    )
    potassium_pct = models.DecimalField(
        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='カリ含有率(%)'
    )
    notes = models.TextField(blank=True, null=True, verbose_name='備考')

    class Meta:
        verbose_name = '肥料マスタ'
        verbose_name_plural = '肥料マスタ'
        ordering = ['name']

    def __str__(self):
        return self.name


class FertilizationPlan(models.Model):
    name = models.CharField(max_length=200, verbose_name='計画名')
    year = models.IntegerField(verbose_name='年度')
    variety = models.ForeignKey(
        'plans.Variety', on_delete=models.PROTECT,
        related_name='fertilization_plans', verbose_name='品種'
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        verbose_name = '施肥計画'
        verbose_name_plural = '施肥計画'
        ordering = ['-year', 'variety']

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


class FertilizationEntry(models.Model):
    """圃場 × 肥料 × 袋数 の中間テーブル"""
    plan = models.ForeignKey(
        FertilizationPlan, on_delete=models.CASCADE, related_name='entries'
    )
    field = models.ForeignKey(
        'fields.Field', on_delete=models.CASCADE, verbose_name='圃場'
    )
    fertilizer = models.ForeignKey(
        Fertilizer, on_delete=models.CASCADE, verbose_name='肥料'
    )
    bags = models.DecimalField(max_digits=8, decimal_places=2, verbose_name='袋数')

    class Meta:
        verbose_name = '施肥エントリ'
        verbose_name_plural = '施肥エントリ'
        unique_together = [['plan', 'field', 'fertilizer']]
        ordering = ['field', 'fertilizer']

    def __str__(self):
        return f"{self.plan} / {self.field} / {self.fertilizer}: {self.bags}袋"