from odoo import models


class ProjectTask(models.Model):
    _inherit = 'project.task'

    def get_hierarchy(self, project_id=None):
        """返回项目下任务的树形结构（嵌套 children），供前端 D3 渲染。

        :param project_id: 项目ID，为空则返回所有任务
        :return: 含虚拟根的嵌套字典
        """
        domain = []
        if project_id:
            domain.append(('project_id', '=', project_id))
        tasks = self.search(domain)

        by_id = {}
        for t in tasks:
            by_id[t.id] = {
                'id': t.id,
                'name': t.name or '未命名',
                'parent_id': t.parent_id.id if t.parent_id else None,
                'progress': round(t.progress or 0),
                'user_id': t.user_id.name if t.user_id else False,
                'stage_id': t.stage_id.name if t.stage_id else False,
                'date_deadline': t.date_deadline.strftime('%Y-%m-%d') if t.date_deadline else False,
                'children': [],
            }

        roots = []
        for t in tasks:
            node = by_id[t.id]
            pid = node['parent_id']
            if pid and pid in by_id:
                by_id[pid]['children'].append(node)
            else:
                roots.append(node)

        return {
            'id': 0,
            'name': '项目任务',
            'children': roots,
        }