from odoo import fields, models, api, _
from odoo.exceptions import ValidationError

class IncomeTaxSlabMaster(models.Model):
    _name = 'it.slab.master'
    _description = 'Income Tax Slab Master'
    _rec_name = 'name'
    _sql_constraints = [
        (
            'unique_slab',
            'unique(regime, age_category, residence_type)',
            'Slab must be unique for the same Regime, Age Category, and Residence Type!'
        )
    ]

    name = fields.Char(string="Slab Name", required=True)
    regime = fields.Selection([
        ('old', 'Old Tax Regime'),
        ('new', 'New Tax Regime')
    ], required=True)
    age_category = fields.Selection([
        ('below_60', 'Below 60 Years'),
        ('60_to_80', '60-80 Years'),
        ('above_80', 'Above 80 Years')
    ], required=True)
    residence_type = fields.Selection([
        ('resident', 'Resident'),
        ('non_resident', 'Non Resident'),
        ('both', 'Both')
    ], required=True)
    standard_deduction = fields.Float(string="Standard Deduction")
    active = fields.Boolean(default=True)
    rules = fields.One2many('it.slab.master.rules','slab_id', string="Slab Rules")

class IncomeTaxSlabMasterRules(models.Model):
    _name = 'it.slab.master.rules'
    _description = 'Income Tax slab rules'
    _rec_name = 'slab_id'
    _sql_constraints = [
        (
            'check_min_max_income',
            'CHECK (max_income IS NULL OR max_income > min_income)',
            'Max Income must be greater than Min Income!'
        )
    ]

    min_income = fields.Float(string="Min Income (₹)", required=True)
    max_income = fields.Float(string="Max Income (₹)")
    tax_rate = fields.Float(string="Tax Rate (%)", required=True)
    fixed_amount = fields.Float(string="Fixed Amount (₹)")
    excess_threshold = fields.Float(string="Excess Threshold (₹)")
    surcharge_rate = fields.Float(string="Surcharge Rate (%)")
    cess_rate = fields.Float(string="Health & Education (%)", default=4.0)
    slab_id = fields.Many2one('it.slab.master')



    @api.constrains('min_income', 'max_income', 'slab_id')
    def _check_overlap(self):
        """Ensure no overlapping or duplicate ranges within the same slab"""
        for rule in self:
            domain = [
                ('slab_id', '=', rule.slab_id.id),
                ('id', '!=', rule.id)
            ]
            others = self.search(domain)
            for other in others:
                if not (rule.max_income and other.min_income >= rule.max_income) and \
                        not (other.max_income and rule.min_income >= other.max_income):
                    raise ValidationError(
                        f"Income ranges overlap with another slab rule: {other.min_income} - {other.max_income}"
                    )