from jinja2 import Environment, FileSystemLoader, ChoiceLoader
from sqlalchemy.orm import class_mapper, RelationshipProperty
from flask import current_app
import os

def get_env():
    app_loader = current_app.jinja_loader

    default_path = os.path.join(os.path.dirname(__file__), 'templates')
    fallback_loader = FileSystemLoader(default_path)

    env = Environment(loader=ChoiceLoader([
        app_loader,
        fallback_loader
    ]))
    return env

def get_crudkit_template(env, name):
    try:
        return env.get_template(f'crudkit/{name}')
    except Exception:
        return env.get_template(name)

def render_field(field, value):
    env = get_env()
    template = get_crudkit_template(env, 'field.html')
    return template.render(
        field_name=field['name'],
        field_label=field.get('label', field['name']),
        value=value,
        field_type=field.get('type', 'text'),
        options=field.get('options', None)
    )

def render_table(objects):
    env = get_env()
    template = get_crudkit_template(env, 'table.html')
    return template.render(objects=objects)

def render_form(model_cls, values, session=None):
    env = get_env()
    template = get_crudkit_template(env, 'form.html')
    fields = []
    fk_fields = set()

    mapper = class_mapper(model_cls)
    for prop in mapper.iterate_properties:
        # FK Relationship fields (many-to-one)
        if isinstance(prop, RelationshipProperty) and prop.direction.name == 'MANYTOONE':
            if session is None:
                continue

            related_model = prop.mapper.class_
            options = session.query(related_model).all()
            fields.append({
                'name': f"{prop.key}_id",
                'label': prop.key,
                'type': 'select',
                'options': [
                    {'value': getattr(obj, 'id'), 'label': str(obj)}
                    for obj in options
                ]
            })
            fk_fields.add(f"{prop.key}_id")

    # Now add basic columns — excluding FKs already covered
    for col in model_cls.__table__.columns:
        if col.name in fk_fields:
            continue
        if col.name in ('id', 'created_at', 'updated_at'):
            continue
        if col.default or col.server_default or col.onupdate:
            continue
        fields.append({
            'name': col.name,
            'label': col.name,
            'type': 'text',
        })

    return template.render(fields=fields, values=values, render_field=render_field)