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

class EducationExamMarksEntryWizard(models.TransientModel):
    _name = 'education.exam.marks.entry.wizard'
    _description = 'Subject-wise Marks Entry Wizard'

    exam_id = fields.Many2one(
        'education.exam',
        string='Exam',
        required=True,
        domain="[('state', 'in', ['ongoing', 'completed'])]"
    )
    subject_id = fields.Many2one(
        'education.subject',
        string='Subject',
        required=True
    )
    max_marks = fields.Float(string='Maximum Marks', readonly=True)
    pass_marks = fields.Float(string='Pass Marks', readonly=True)
    faculty_id = fields.Many2one('res.users', string='Assigned Faculty', readonly=True)
    line_ids = fields.One2many(
        'education.exam.marks.entry.wizard.line',
        'wizard_id',
        string='Student Marks'
    )

    @api.onchange('exam_id')
    def _onchange_exam_id(self):
        self.subject_id = False
        self.line_ids = [(5, 0, 0)]
        if self.exam_id:
            # Restrict subject domain to subjects scheduled in this exam
            subject_ids = self.exam_id.line_ids.mapped('subject_id.id')
            return {'domain': {'subject_id': [('id', 'in', subject_ids)]}}
        return {'domain': {'subject_id': []}}

    @api.onchange('exam_id', 'subject_id')
    def _onchange_exam_and_subject(self):
        if self.exam_id and self.subject_id:
            self._check_teacher_authorization()
            self._load_subject_details()
            self._load_student_lines()

    def _check_teacher_authorization(self):
        self.ensure_one()
        if not self.env.user.has_group('education_exam.group_education_exam_administrator'):
            schedule_line = self.env['education.exam.line'].search([
                ('exam_id', '=', self.exam_id.id),
                ('subject_id', '=', self.subject_id.id),
            ], limit=1)
            if schedule_line and schedule_line.faculty_id and schedule_line.faculty_id != self.env.user:
                raise ValidationError(
                    f"Access Denied: You are not authorized to enter marks for subject '{self.subject_id.name}'. "
                    f"This subject is assigned to {schedule_line.faculty_id.name}."
                )

    def _load_subject_details(self):
        schedule_line = self.env['education.exam.line'].search([
            ('exam_id', '=', self.exam_id.id),
            ('subject_id', '=', self.subject_id.id),
        ], limit=1)
        if schedule_line:
            self.max_marks = schedule_line.max_marks
            self.pass_marks = schedule_line.pass_marks
            self.faculty_id = schedule_line.faculty_id.id
        else:
            self.max_marks = 0.0
            self.pass_marks = 0.0
            self.faculty_id = False

    def _load_student_lines(self):
        self.line_ids = [(5, 0, 0)]
        result_lines = self.env['education.exam.result.line'].sudo().search([
            ('result_id.exam_id', '=', self.exam_id.id),
            ('subject_id', '=', self.subject_id.id),
        ])
        lines = []
        for rl in result_lines:
            student = rl.result_id.student_id.sudo()
            lines.append((0, 0, {
                'result_line_id': rl.id,
                'student_id': student.id,
                'roll_number': student.roll_number or '',
                'admission_number': student.admission_number or '',
                'obtained_marks': rl.obtained_marks,
                'remarks': rl.remarks or '',
            }))
        self.line_ids = lines

    def action_load_students(self):
        """Action button to reload student lines explicitly."""
        self.ensure_one()
        self._check_teacher_authorization()
        self._load_subject_details()
        self._load_student_lines()
        return {'type': 'ir.actions.do_nothing'}

    def action_save_marks(self):
        self.ensure_one()
        self._check_teacher_authorization()
        if self.exam_id.state == 'results_published':
            raise ValidationError("Cannot save marks for published exams. Results must be unpublished first.")

        if not self.line_ids:
            raise ValidationError("No student marks to save. Please select a valid exam and subject, or generate results first.")

        for line in self.line_ids:
            if line.obtained_marks < -1.0:
                raise ValidationError(
                    f"Marks for student '{line.student_id.full_name}' cannot be negative (use -1 for pending)."
                )
            if line.obtained_marks > self.max_marks:
                raise ValidationError(
                    f"Marks for student '{line.student_id.full_name}' ({line.obtained_marks}) "
                    f"cannot exceed maximum marks ({self.max_marks})."
                )
            if line.result_line_id:
                line.result_line_id.write({
                    'obtained_marks': line.obtained_marks,
                    'remarks': line.remarks,
                })

        return {
            'type': 'ir.actions.client',
            'tag': 'display_notification',
            'params': {
                'title': 'Marks Saved',
                'message': f"Marks successfully saved for '{self.subject_id.name}'.",
                'type': 'success',
                'sticky': False,
                'next': {'type': 'ir.actions.act_window_close'},
            }
        }


class EducationExamMarksEntryWizardLine(models.TransientModel):
    _name = 'education.exam.marks.entry.wizard.line'
    _description = 'Subject-wise Marks Entry Wizard Line'

    wizard_id = fields.Many2one(
        'education.exam.marks.entry.wizard',
        string='Wizard',
        required=True,
        ondelete='cascade'
    )
    result_line_id = fields.Many2one('education.exam.result.line', string='Exam Result Line')
    student_id = fields.Many2one('education.student', string='Student', required=True)
    roll_number = fields.Char(string='Roll No.', readonly=True)
    admission_number = fields.Char(string='Admission No.', readonly=True)
    obtained_marks = fields.Float(string='Obtained Marks', default=-1.0, required=True)
    remarks = fields.Char(string='Remarks')