import base64

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


class CommunitySchoolAssignment(models.Model):
    _name = 'community.school.assignment'
    _description = 'School Assignment'
    _order = 'due_date asc, id desc'
    _inherit = ['mail.thread', 'mail.activity.mixin']

    name = fields.Char(string='Title', required=True, tracking=True)
    class_id = fields.Many2one(
        'community.school.class', string='Class', required=True, ondelete='cascade',
    )
    term_id = fields.Many2one(related='class_id.term_id', store=True)
    teacher_id = fields.Many2one(related='class_id.teacher_id', store=True)
    description = fields.Html(string='Instructions')
    due_date = fields.Datetime(string='Due Date', required=True, tracking=True)
    max_score = fields.Integer(string='Max Score', default=100)
    state = fields.Selection(
        [('draft', 'Draft'), ('published', 'Published'), ('closed', 'Closed')],
        default='draft', required=True, tracking=True,
    )
    submission_ids = fields.One2many('community.school.submission', 'assignment_id')
    submission_count = fields.Integer(compute='_compute_submission_count', store=True)

    @api.depends('submission_ids')
    def _compute_submission_count(self):
        for assignment in self:
            assignment.submission_count = len(assignment.submission_ids)

    def action_publish(self):
        for rec in self:
            rec.state = 'published'

    def action_close(self):
        for rec in self:
            rec.state = 'closed'

    def action_reset_draft(self):
        for rec in self:
            rec.state = 'draft'

    def action_view_submissions(self):
        self.ensure_one()
        return {
            'type': 'ir.actions.act_window',
            'name': f'Submissions – {self.name}',
            'res_model': 'community.school.submission',
            'view_mode': 'list,form',
            'domain': [('assignment_id', '=', self.id)],
            'context': {'default_assignment_id': self.id},
        }


class CommunitySchoolSubmission(models.Model):
    _name = 'community.school.submission'
    _description = 'Assignment Submission'
    _order = 'submitted_on desc, id desc'

    assignment_id = fields.Many2one(
        'community.school.assignment', required=True, ondelete='cascade',
    )
    enrollment_id = fields.Many2one(
        'community.school.enrollment', string='Student Enrollment', required=True, ondelete='cascade',
    )
    student_id = fields.Many2one(related='enrollment_id.student_id', store=True)
    class_id = fields.Many2one(related='assignment_id.class_id', store=True)

    submitted_on = fields.Datetime(string='Submitted On', readonly=True)
    notes = fields.Text(string='Student Notes')

    # File attachment stored as binary
    attachment_name = fields.Char(string='File Name')
    attachment_data = fields.Binary(string='Uploaded File', attachment=True)

    # Grading
    score = fields.Integer(string='Score')
    feedback = fields.Text(string='Teacher Feedback')
    state = fields.Selection(
        [('submitted', 'Submitted'), ('graded', 'Graded')],
        default='submitted', required=True,
    )
    is_late = fields.Boolean(compute='_compute_is_late', store=True)

    _assignment_enrollment_uniq = models.Constraint(
        'unique(assignment_id, enrollment_id)',
        'A submission for this assignment by this student already exists.',
    )

    @api.depends('submitted_on', 'assignment_id.due_date')
    def _compute_is_late(self):
        for sub in self:
            if sub.submitted_on and sub.assignment_id.due_date:
                sub.is_late = sub.submitted_on > sub.assignment_id.due_date
            else:
                sub.is_late = False

    @api.constrains('score', 'assignment_id')
    def _check_score(self):
        for sub in self:
            if sub.score < 0:
                raise ValidationError('Score cannot be negative.')
            if sub.assignment_id and sub.score > sub.assignment_id.max_score:
                raise ValidationError(
                    f'Score ({sub.score}) cannot exceed max score ({sub.assignment_id.max_score}).'
                )

    def action_grade(self):
        for sub in self:
            sub.state = 'graded'