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

class SchoolGradesheetLine(models.Model):
    _name = 'school.gradesheet.line'
    _description = 'Student Grade Line'
    _order = 'student_name'

    gradesheet_id = fields.Many2one('school.gradesheet', string="Gradesheet", ondelete="cascade")
    application_id = fields.Many2one('school.application', string="Application", required=True)
    student_id = fields.Many2one('school.application', string="Student", required=True)
    student_name = fields.Char(related='student_id.name', string="Student Name", store=True)
    roll_number = fields.Char(related='student_id.roll_no', string="Roll Number", store=True)
    subject_id = fields.Many2one('school.subject', string="Subject")


    enrollment_id = fields.Many2one(
        'school.enrollment',
        string="Enrollment"
    )
     
    obtained_marks = fields.Float(
        string="Obtained Marks",
        default=0.0
    )
    total_marks = fields.Float(
        string="Total Marks",
        default=100.0
    )
    percentage = fields.Float(
        string="Percentage (%)",
        compute="_compute_percentage",
        store=True
    )

    # Grade Info
    final_grade = fields.Selection([
        ('A+', 'A+ (90-100%)'),
        ('A', 'A (80-89%)'),
        ('B+', 'B+ (70-79%)'),
        ('B', 'B (60-69%)'),
        ('C', 'C (50-59%)'),
        ('D', 'D (40-49%)'),
        ('F', 'F (Below 40%)')
    ], string="Grade", default='F')

    status = fields.Selection([
        ('pass', 'Pass'),
        ('fail', 'Fail')
    ], string="Status", default='fail')

    remarks = fields.Text(string="Remarks")

    # Compute percentage
    @api.depends('obtained_marks', 'total_marks')
    def _compute_percentage(self):
        for record in self:
            if record.total_marks > 0:
                record.percentage = (record.obtained_marks / record.total_marks) * 100
            else:
                record.percentage = 0.0

    # Auto-update grade and status on marks change
    @api.onchange('obtained_marks', 'total_marks')
    def _onchange_marks(self):
        for record in self:
            if record.total_marks > 0:
                percentage = (record.obtained_marks / record.total_marks) * 100

                if percentage >= 90:
                    record.final_grade = 'A+'
                    record.status = 'pass'
                elif percentage >= 80:
                    record.final_grade = 'A'
                    record.status = 'pass'
                elif percentage >= 70:
                    record.final_grade = 'B+'
                    record.status = 'pass'
                elif percentage >= 60:
                    record.final_grade = 'B'
                    record.status = 'pass'
                elif percentage >= 50:
                    record.final_grade = 'C'
                    record.status = 'pass'
                elif percentage >= 40:
                    record.final_grade = 'D'
                    record.status = 'pass'
                else:
                    record.final_grade = 'F'
                    record.status = 'fail'
            else:
                record.percentage = 0.0
                record.final_grade = 'F'
                record.status = 'fail'

    # Validation to prevent invalid marks
    @api.constrains('obtained_marks', 'total_marks')
    def _check_marks(self):
        for record in self:
            if record.obtained_marks < 0 or record.total_marks < 0:
                raise ValidationError("Marks cannot be negative.")
            if record.obtained_marks > record.total_marks:
                raise ValidationError("Obtained marks cannot exceed total marks.")