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


class EducationLibraryIssue(models.Model):
    _name = 'education.library.issue'
    _description = 'Library Book Issue'
    _rec_name = 'name'
    _order = 'issue_date desc'

    name = fields.Char(string='Reference', required=True, copy=False, readonly=True, default=lambda self: _('New'))
    member_id = fields.Many2one('education.library.member', string='Member', required=True)
    copy_id = fields.Many2one('education.library.book.copy', string='Book Copy', required=True)
    library_id = fields.Many2one('education.library', string='Library', related='copy_id.library_id', store=True)
    
    issue_date = fields.Date(string='Issue Date', default=fields.Date.context_today, required=True)
    due_date = fields.Date(string='Due Date', compute='_compute_due_date', store=True, readonly=False)
    return_date = fields.Date(string='Return Date')
    
    status = fields.Selection([
        ('draft', 'Draft'),
        ('issued', 'Issued'),
        ('returned', 'Returned'),
        ('overdue', 'Overdue'),
        ('cancelled', 'Cancelled')
    ], string='Status', default='draft', required=True)
    
    remarks = fields.Text(string='Remarks')
    fine_amount = fields.Float(string='Fine Amount', compute='_compute_fine_amount')
    fine_ids = fields.One2many('education.library.fine', 'issue_id', string='Fines')

    @api.model_create_multi
    def create(self, vals_list):
        for vals in vals_list:
            if vals.get('name', _('New')) == _('New'):
                vals['name'] = self.env['ir.sequence'].sudo().next_by_code('education.library.issue') or _('New')
        return super().create(vals_list)

    @api.depends('issue_date')
    def _compute_due_date(self):
        loan_days = int(self.env['ir.config_parameter'].sudo().get_param('education_library.loan_period_days', 14))
        for record in self:
            if record.issue_date and not record.due_date:
                record.due_date = record.issue_date + timedelta(days=loan_days)

    @api.depends('fine_ids', 'fine_ids.amount')
    def _compute_fine_amount(self):
        for record in self:
            record.fine_amount = sum(record.fine_ids.mapped('amount'))

    @api.constrains('issue_date', 'due_date')
    def _check_dates(self):
        for record in self:
            if record.due_date < record.issue_date:
                raise ValidationError(_('Due date must be greater than or equal to issue date.'))

    def action_issue(self):
        for record in self:
            if record.copy_id.status != 'available':
                raise ValidationError(_('The selected book copy is not available for issue.'))
            if not record.member_id.active:
                raise ValidationError(_('Active member required.'))
            if record.member_id.membership_end and record.member_id.membership_end < fields.Date.today():
                raise ValidationError(_('Membership dates do not permit issue.'))
            
            # Check issue limit
            active_issues = self.search_count([
                ('member_id', '=', record.member_id.id),
                ('status', 'in', ['issued', 'overdue'])
            ])
            if active_issues >= record.member_id.issue_limit:
                raise ValidationError(_('Issue limit enforced: Member has reached their maximum active issues limit.'))

            record.copy_id.status = 'issued'
            record.status = 'issued'

    def action_return(self):
        for record in self:
            if record.status not in ['issued', 'overdue']:
                raise ValidationError(_('Only issued or overdue records can be returned.'))
            
            return_date = fields.Date.today()
            record.return_date = return_date
            
            # Calculate fine if late
            days_late = max((return_date - record.due_date).days, 0)
            if days_late > 0:
                fine_per_day = float(self.env['ir.config_parameter'].sudo().get_param('education_library.fine_per_day', 10.0))
                fine_amt = days_late * fine_per_day
                if fine_amt > 0:
                    self.env['education.library.fine'].create({
                        'issue_id': record.id,
                        'member_id': record.member_id.id,
                        'student_id': record.member_id.student_id.id if record.member_id.student_id else False,
                        'days_late': days_late,
                        'amount': fine_amt,
                        'state': 'draft'
                    })

            record.copy_id.status = 'available'
            record.status = 'returned'

    def action_cancel(self):
        for record in self:
            if record.status not in ['draft']:
                raise ValidationError(_('Only draft issues can be cancelled.'))
            record.status = 'cancelled'

    @api.model
    def _cron_mark_overdue(self):
        overdue_issues = self.search([
            ('status', '=', 'issued'),
            ('due_date', '<', fields.Date.today())
        ])
        overdue_issues.write({'status': 'overdue'})