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


class DanceEnrollment(models.Model):
    _name = "dance.enrollment"
    _description = "Dance Enrollment"
    _order = "enrollment_date desc, id desc"

    name = fields.Char(compute="_compute_name", store=True)
    student_id = fields.Many2one(
        "res.partner",
        required=True,
        domain="[('is_student', '=', True)]",
        ondelete="restrict",
    )
    batch_id = fields.Many2one(
        "dance.batch",
        required=True,
        ondelete="restrict",
    )
    enrollment_date = fields.Date(default=fields.Date.context_today, required=True)
    status = fields.Selection(
        [
            ("active", "Active"),
            ("hold", "Hold"),
            ("dropped", "Dropped"),
            ("completed", "Completed"),
        ],
        default="active",
        required=True,
    )
    notes = fields.Text()

    _sql_constraints = [
        (
            "student_batch_unique",
            "unique(student_id, batch_id)",
            "This student is already enrolled in this batch.",
        ),
    ]

    @api.depends("student_id", "batch_id")
    def _compute_name(self):
        for enrollment in self:
            if enrollment.student_id and enrollment.batch_id:
                enrollment.name = "%s - %s" % (
                    enrollment.student_id.display_name,
                    enrollment.batch_id.name,
                )
            else:
                enrollment.name = "New Enrollment"

    @api.constrains("batch_id", "status")
    def _check_batch_capacity(self):
        for enrollment in self:
            if enrollment.status != "active" or not enrollment.batch_id.capacity:
                continue
            active_count = self.search_count(
                [
                    ("batch_id", "=", enrollment.batch_id.id),
                    ("status", "=", "active"),
                    ("id", "!=", enrollment.id),
                ]
            )
            if active_count + 1 > enrollment.batch_id.capacity:
                raise ValidationError("This batch is already at full capacity.")

    @api.constrains("student_id")
    def _check_student_flag(self):
        for enrollment in self:
            if enrollment.student_id and not enrollment.student_id.is_student:
                raise ValidationError("Only student contacts can be enrolled in a batch.")

    @api.onchange("batch_id", "status")
    def _onchange_batch_capacity_warning(self):
        if (
            self.batch_id
            and self.status == "active"
            and self.batch_id.capacity
            and self.batch_id.active_enrollment_count < self.batch_id.capacity
            and self.batch_id.available_seats <= 2
        ):
            return {
                "warning": {
                    "title": "Batch almost full",
                    "message": "Batch almost full (%s/%s)."
                    % (
                        self.batch_id.active_enrollment_count,
                        self.batch_id.capacity,
                    ),
                }
            }
        return {}