from django.db import models
from django.contrib.auth.models import User
import uuid

# Enums
class CurrencyEnum(models.TextChoices):
    CLP = 'CLP', 'Pesos Chilenos'
    USD = 'USD', 'Dólares Estadounidenses'

class TaxTypeEnum(models.TextChoices):
    EXENTO = 'EXENTO', 'Exento / No Afecto'
    IVA_19 = 'IVA_19', 'Afecto a IVA (19%)'
    HONORARIOS = 'HONORARIOS_13_75', 'Boleta de Honorarios (13.75%)'

class ExpenseTypeEnum(models.TextChoices):
    COSTO_DIRECTO = 'COSTO_DIRECTO_PROYECTO', 'Costo Directo Proyecto'
    GASTO_OPERACIONAL = 'GASTO_OPERACIONAL_OVERHEAD', 'Gasto Operacional Overhead'

class ApprovalStatusEnum(models.TextChoices):
    EN_REVISION = 'EN_REVISION_DOCUMENTAL', 'En Revisión Documental (Paso 1)'
    SOLICITADO_FINANZAS = 'SOLICITADO_FINANZAS', 'Solicitado a Finanzas (Paso 2)'
    LIBERADO_PAGADO = 'LIBERADO_PAGADO', 'Pago Liberado (Paso 3)'
    OBSERVADO_RECHAZADO = 'OBSERVADO_RECHAZADO', 'Observado / Rechazado'

class ProjectStatusEnum(models.TextChoices):
    ACTIVO = 'ACTIVO', 'Activo'
    PAUSADA = 'PAUSADA', 'En Pausa'
    TERMINADO = 'TERMINADO', 'Terminado'

class Project(models.Model):
    # Added core project/costcenter fields mapped from Prisma
    code = models.CharField(max_length=50, unique=True, verbose_name="Código", default='PROY-000')
    name = models.CharField(max_length=200, verbose_name="Nombre del Proyecto/Centro")
    description = models.TextField(blank=True, verbose_name="Descripción")
    
    manager = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='managed_projects', verbose_name="Encargado")
    parent = models.ForeignKey('self', on_delete=models.CASCADE, null=True, blank=True, related_name='children', verbose_name="Portafolio / Proyecto Padre")
    
    assigned_budget_clp = models.DecimalField(max_digits=15, decimal_places=2, default=0, verbose_name="Presupuesto Asignado (CLP)")
    assigned_budget_usd = models.DecimalField(max_digits=15, decimal_places=2, default=0, verbose_name="Presupuesto Asignado (USD)")
    actual_cost_clp = models.DecimalField(max_digits=15, decimal_places=2, default=0, verbose_name="Costo Real Acumulado (CLP)")
    
    type = models.CharField(max_length=50, choices=ExpenseTypeEnum.choices, default=ExpenseTypeEnum.COSTO_DIRECTO, verbose_name="Tipo de Centro")
    status = models.CharField(max_length=50, choices=ProjectStatusEnum.choices, default=ProjectStatusEnum.ACTIVO, verbose_name="Estado de Proyecto")
    category = models.ForeignKey('Category', on_delete=models.SET_NULL, null=True, blank=True, related_name='projects', verbose_name="Categoría del Proyecto")

    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Fecha de Creación")
    updated_at = models.DateTimeField(auto_now=True, verbose_name="Última Modificación")
    created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='created_projects', verbose_name="Creado por")

    def __str__(self):
        return f"{self.code} - {self.name}"
    
    class Meta:
        verbose_name = "Proyecto / Centro de Costo"
        verbose_name_plural = "Proyectos y Centros"

class Category(models.Model):
    code = models.CharField(max_length=10, unique=True, verbose_name="Código de Categoría")
    name = models.CharField(max_length=100, verbose_name="Nombre de Categoría")
    description = models.TextField(blank=True, verbose_name="Descripción")
    parent = models.ForeignKey('self', on_delete=models.CASCADE, null=True, blank=True, related_name='children', verbose_name="Categoría Padre")

    def __str__(self):
        return f"{self.code}: {self.name}"
    
    class Meta:
        verbose_name = "Categoría"
        verbose_name_plural = "Categorías"

class Vendor(models.Model):
    rut = models.CharField(max_length=15, unique=True, verbose_name="RUT Proveedor")
    name = models.CharField(max_length=200, verbose_name="Razón Social / Nombre")
    business_line = models.CharField(max_length=200, blank=True, null=True, verbose_name="Giro Comercial")
    
    # Banking details
    bank = models.CharField(max_length=100, blank=True, null=True, verbose_name="Banco")
    account_type = models.CharField(max_length=50, blank=True, null=True, verbose_name="Tipo de Cuenta")
    account_number = models.CharField(max_length=50, blank=True, null=True, verbose_name="Número de Cuenta")
    email = models.EmailField(blank=True, null=True, verbose_name="Correo de Pago/Facturación")
    
    payment_terms = models.IntegerField(default=30, verbose_name="Plazo de Pago (Días)")
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

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

    class Meta:
        verbose_name = "Proveedor"
        verbose_name_plural = "Proveedores"
        ordering = ['name']

class Expense(models.Model):
    expense_code = models.CharField(max_length=50, unique=True, default=uuid.uuid4, verbose_name="Código Transacción")
    project = models.ForeignKey(Project, on_delete=models.CASCADE, related_name='expenses', verbose_name="Proyecto")
    category = models.ForeignKey(Category, on_delete=models.SET_NULL, null=True, blank=True, related_name='expenses', verbose_name="Subcategoría")
    
    # Financial fields
    amount_clp = models.DecimalField(max_digits=15, decimal_places=2, verbose_name="Monto Neto (CLP)")
    tax_type = models.CharField(max_length=20, choices=TaxTypeEnum.choices, default=TaxTypeEnum.IVA_19, verbose_name="Tipo de Impuesto")
    tax_amount_clp = models.DecimalField(max_digits=15, decimal_places=2, default=0, verbose_name="Monto Impuesto (CLP)")
    total_amount_clp = models.DecimalField(max_digits=15, decimal_places=2, default=0, verbose_name="Monto Total (CLP)")
    
    amount_usd = models.DecimalField(max_digits=15, decimal_places=2, verbose_name="Monto Total (USD)")
    currency = models.CharField(max_length=10, choices=CurrencyEnum.choices, default=CurrencyEnum.CLP, verbose_name="Moneda Original")
    exchange_rate = models.DecimalField(max_digits=10, decimal_places=2, default=950.0, verbose_name="Tipo de Cambio")
    
    description = models.TextField(verbose_name="Detalle de Imputación")
    date = models.DateField(verbose_name="Fecha del Gasto")
    
    vendor = models.ForeignKey(Vendor, on_delete=models.SET_NULL, null=True, blank=True, related_name='expenses', verbose_name="Proveedor / Emisor")
    
    # Geographic & Logistic fields (Operaciones en terreno)
    region = models.CharField(max_length=100, blank=True, null=True, verbose_name="Región (Chile)")
    comuna = models.CharField(max_length=100, blank=True, null=True, verbose_name="Comuna")
    vehicle_ownership = models.CharField(max_length=100, blank=True, null=True, verbose_name="Modalidad / Vehículo")

    # 3-step Approval Flow Tracking
    approval_status = models.CharField(max_length=50, choices=ApprovalStatusEnum.choices, default=ApprovalStatusEnum.EN_REVISION, verbose_name="Estado de Aprobación")
    
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='expenses_created', verbose_name="Registrado por")
    responsible_person = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, related_name='expenses_responsible', verbose_name="Responsable Solicitante")
    elevated_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='expenses_elevated', verbose_name="Elevado por (Paso 2)")
    paid_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='expenses_paid', verbose_name="Pagado por (Paso 3)")
    
    rejection_reason = models.TextField(blank=True, null=True, verbose_name="Motivo de Observación/Rechazo")
    paid_at = models.DateTimeField(null=True, blank=True, verbose_name="Fecha de Pago")

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return f"{self.expense_code} - {self.amount_clp} CLP ({self.date})"
    
    class Meta:
        verbose_name = "Gasto"
        verbose_name_plural = "Gastos"
        ordering = ['-date', '-created_at']

class Document(models.Model):
    expense = models.ForeignKey(Expense, on_delete=models.CASCADE, related_name='documents', verbose_name="Gasto Relacionado")
    file = models.FileField(upload_to='evidences/', verbose_name="Archivo Adjunto")
    file_type = models.CharField(max_length=50, blank=True, verbose_name="Tipo de Archivo")
    title = models.CharField(max_length=200, blank=True, verbose_name="Título del Documento")
    uploaded_at = models.DateTimeField(auto_now_add=True, verbose_name="Fecha de Subida")
    uploaded_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, verbose_name="Subido por")

    def __str__(self):
        return f"Evidencia para {self.expense.expense_code}"

    class Meta:
        verbose_name = "Documento Evidencia"
        verbose_name_plural = "Documentos Evidencias"

class UserProfile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE, related_name='profile', verbose_name="Usuario")
    rut = models.CharField(max_length=20, blank=True, null=True, verbose_name="RUT")
    job_title = models.CharField(max_length=150, blank=True, null=True, verbose_name="Cargo")
    description = models.TextField(blank=True, verbose_name="Descripción del Responsable")
    specialties = models.ManyToManyField('Category', blank=True, related_name='specialists', verbose_name="Especialidades / Habilidades")
    
    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Fecha de Registro")
    updated_at = models.DateTimeField(auto_now=True, verbose_name="Última Modificación")

    def __str__(self):
        return f"Perfil de {self.user.username}"
    
    class Meta:
        verbose_name = "Perfil de Usuario"
        verbose_name_plural = "Perfiles de Usuario"

class AuditLog(models.Model):
    user = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, verbose_name="Usuario")
    action = models.CharField(max_length=100, verbose_name="Acción")
    entity_name = models.CharField(max_length=100, blank=True, null=True, verbose_name="Entidad (Tabla)")
    entity_id = models.CharField(max_length=100, blank=True, null=True, verbose_name="ID Entidad")
    field_changed = models.CharField(max_length=100, blank=True, null=True, verbose_name="Campo Modificado")
    old_value = models.TextField(blank=True, null=True, verbose_name="Valor Anterior")
    new_value = models.TextField(blank=True, null=True, verbose_name="Valor Nuevo")
    
    description = models.TextField(verbose_name="Detalle del Cambio")
    timestamp = models.DateTimeField(auto_now_add=True, verbose_name="Fecha y Hora")

    def __str__(self):
        return f"{self.timestamp} - {self.user.username if self.user else 'Sistema'}: {self.action}"

    class Meta:
        ordering = ['-timestamp']
        verbose_name = "Log de Auditoría (SAP CDHDR/CDPOS)"
        verbose_name_plural = "Logs de Auditoría"

class SystemSetting(models.Model):
    global_budget = models.DecimalField(max_digits=15, decimal_places=2, default=25000000.00, verbose_name="Presupuesto General I+D+i")
    usd_exchange_rate = models.DecimalField(max_digits=10, decimal_places=2, default=950.0, verbose_name="Tasa USD/CLP por Defecto")
    
    def __str__(self):
        return "Configuración Global EFINTEL"

    class Meta:
        verbose_name = "Configuración del Sistema"
        verbose_name_plural = "Configuraciones del Sistema"