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')
    material = models.OneToOneField(
        'materials.Material',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='legacy_fertilizer',
        verbose_name='資材マスタ',
    )

    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'
    )
    calc_settings = models.JSONField(default=list, blank=True, verbose_name='計算設定')
    is_confirmed = models.BooleanField(default=False, verbose_name='散布確定済み')
    confirmed_at = models.DateTimeField(null=True, blank=True, verbose_name='散布確定日時')
    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.PROTECT, 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"


class DistributionPlan(models.Model):
    """分配計画：施肥計画の圃場をカスタムグループに割り当て、配置場所単位で集計する"""
    fertilization_plan = models.ForeignKey(
        FertilizationPlan, on_delete=models.CASCADE,
        related_name='distribution_plans', verbose_name='施肥計画'
    )
    name = models.CharField(max_length=200, verbose_name='計画名')
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        verbose_name = '分配計画'
        verbose_name_plural = '分配計画'
        ordering = ['-fertilization_plan__year', 'name']

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


class DistributionGroup(models.Model):
    """分配グループ：ある場所にまとめて置く圃場のグループ"""
    distribution_plan = models.ForeignKey(
        DistributionPlan, on_delete=models.CASCADE,
        related_name='groups', verbose_name='分配計画'
    )
    name = models.CharField(max_length=100, verbose_name='グループ名')
    order = models.PositiveIntegerField(default=0, verbose_name='表示順')

    class Meta:
        verbose_name = '分配グループ'
        verbose_name_plural = '分配グループ'
        unique_together = [['distribution_plan', 'name']]
        ordering = ['order', 'id']

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


class DistributionGroupField(models.Model):
    """圃場のグループへの割り当て（1圃場=1グループ/1分配計画）"""
    distribution_plan = models.ForeignKey(
        DistributionPlan, on_delete=models.CASCADE, verbose_name='分配計画'
    )
    group = models.ForeignKey(
        DistributionGroup, on_delete=models.CASCADE,
        related_name='field_assignments', verbose_name='グループ'
    )
    field = models.ForeignKey(
        'fields.Field', on_delete=models.PROTECT, verbose_name='圃場'
    )

    class Meta:
        verbose_name = 'グループ圃場割り当て'
        verbose_name_plural = 'グループ圃場割り当て'
        unique_together = [['distribution_plan', 'field']]
        ordering = ['field__display_order', 'field__id']

    def __str__(self):
        return f"{self.group.name} / {self.field.name}"