after_install = "my_app.install.after_install"
after_migrate = "my_app.install.after_migrate"

import frappe
from frappe.custom.doctype.custom_field.custom_field import create_custom_fields

# The existing OLD_FIELDS will always be deleted first.
# Make sure to include all fields that you create in this list.
# When removing a field from the CUSTOM_FIELDS list, keep its entry in the OLD_FIELDS.
# This will ensure that future migrations will correctly remove obsolete fields.
# The fields will be created in module MODULE.
# System generated property setters are always removed before migrate.
# Make sure to keep them in the PROPERTY_SETTERS list until they become obsolete.

MODULE = "My App"

OLD_FIELDS = [
    ("Customer", "my_field"),
]

CUSTOM_FIELDS = {
    "Customer": [
        {
            "fieldname": "my_app_field",
            "label": "My Field",
            "fieldtype": "Data",
            "insert_after": "customer_name",
        },
    ],
}

PROPERTY_SETTERS = [
    # {
    #   "name": "DOCTYPE-FIELD-PROPERTY",
    #   "doc_type": "DOCTYPE",
    #   "doctype_or_field": "DocField",
    #   "field_name": "FIELD",
    #   "property": "PROPERTY",
    #   "value": "VALUE",
    # },
]


def after_install():
    after_migrate()


def after_migrate():
    for dt, fieldname in OLD_FIELDS:
        if name := frappe.db.exists("Custom Field", {"dt": dt, "fieldname": fieldname}):
            frappe.delete_doc("Custom Field", name)

    # Add `module` property and `insert_after` if missing
    for fields in CUSTOM_FIELDS.values():
        prev_field = None
        for field in fields:
            field["module"] = MODULE
            if prev_field and not field.get("insert_after"):
                field["insert_after"] = prev_field["fieldname"]
            prev_field = field

    create_custom_fields(CUSTOM_FIELDS)

    # Insert property setters
    for ps in PROPERTY_SETTERS:
        assert ps["name"], "Property Setter name is required"
        frappe.delete_doc_if_exists("Property Setter", ps["name"])

        doc = frappe.new_doc("Property Setter")  # type: ignore
        doc.is_system_generated = True
        doc.module = MODULE
        doc.update(ps)
        doc.insert()