from odoo import models, fields, api
from odoo.exceptions import ValidationError
from datetime import datetime, timedelta
import calendar


class PayrollPeriod(models.Model):
    _name = 'payroll.period'
    _description = 'Payroll Period'
    _rec_name = 'name'
    _sql_constraints = [
        ('unique_name', 'unique(name)', 'The name must be unique.')
    ]

    from_date = fields.Date(string="From Date", required=True)
    to_date = fields.Date(string="To Date", required=True)
    name = fields.Char(string="Name", required=True)
    period_line_ids = fields.One2many('payroll.period.line', 'period_id', string="Monthly Periods")

    @api.onchange('from_date', 'to_date')
    def onchange_from_to_date(self):
        for rec in self:
            if rec.from_date and rec.to_date:
                rec.name = f"{rec.from_date.year}-{rec.to_date.year}"


    def action_generate_month_lines(self):
        self.ensure_one()
        if not (self.from_date and self.to_date):
            raise ValidationError("Please set both From Date and To Date.")

        lines = []
        current = self.from_date.replace(day=1)
        while current <= self.to_date:
            end_of_month = current.replace(day=calendar.monthrange(current.year, current.month)[1])
            if end_of_month > self.to_date:
                end_of_month = self.to_date

            lines.append((0, 0, {
                'from_date': current,
                'to_date': end_of_month,
                'name': f"{current.strftime('%b')} - {str(current.year)[-2:]}"
            }))

            if current.month == 12:
                current = current.replace(year=current.year + 1, month=1)
            else:
                current = current.replace(month=current.month + 1)

        self.period_line_ids = lines


class PayrollPeriodLine(models.Model):
    _name = 'payroll.period.line'
    _description = 'Payroll Period Line'
    _rec_name = 'name'

    period_id = fields.Many2one('payroll.period', string="Payroll Period", required=True, ondelete='cascade')
    from_date = fields.Date(string="From Date")
    to_date = fields.Date(string="To Date")
    name = fields.Char(string="Name")