"""
A nice little admin interface for migrating courses and libraries from modulstore to openedx_content.
"""
import logging

from django import forms
from django.contrib import admin, messages
from django.contrib.admin.helpers import ActionForm
from django.db import models


from opaque_keys import InvalidKeyError
from opaque_keys.edx.locator import LibraryCollectionLocator, LibraryLocatorV2
from user_tasks.models import UserTaskStatus

from openedx.core.types.http import AuthenticatedHttpRequest

from . import api
from .data import CompositionLevel, RepeatHandlingStrategy
from .models import ModulestoreSource, ModulestoreMigration, ModulestoreBlockSource, ModulestoreBlockMigration


log = logging.getLogger(__name__)


class StartMigrationTaskForm(ActionForm):
    """
    Params for start_migration_task admin adtion, displayed next the "Go" button.
    """
    target_key = forms.CharField(label="Target library or collection key →", required=False)
    repeat_handling_strategy = forms.ChoiceField(
        label="How to handle existing content? →",
        choices=RepeatHandlingStrategy.supported_choices,
        required=False,
    )
    preserve_url_slugs = forms.BooleanField(label="Preserve current slugs? →", required=False, initial=True)
    forward_to_target = forms.BooleanField(label="Forward references? →", required=False)
    composition_level = forms.ChoiceField(
        label="Aggregate up to →", choices=CompositionLevel.supported_choices, required=False
    )


def task_status_details(obj: ModulestoreMigration) -> str:
    """
    Return the state and, if available, details of the status of the migration.
    """
    details: str | None = None
    if obj.task_status.state == UserTaskStatus.FAILED:
        # Calling fail(msg) from a task should automatically generates an "Error" artifact with that msg.
        # https://django-user-tasks.readthedocs.io/en/latest/user_tasks.html#user_tasks.models.UserTaskStatus.fail
        if error_artifacts := obj.task_status.artifacts.filter(name="Error"):
            if error_text := error_artifacts.order_by("-created").first().text:
                details = error_text
    elif obj.task_status.state == UserTaskStatus.SUCCEEDED:
        details = f"Migrated {obj.block_migrations.count()} blocks"
    return f"{obj.task_status.state}: {details}" if details else obj.task_status.state


migration_admin_fields = (
    "target",
    "target_collection",
    "task_status",
    # The next line works, but django-stubs incorrectly thinks that these should all be strings,
    # so we will need to use type:ignore below.
    task_status_details,
    "composition_level",
    "repeat_handling_strategy",
    "preserve_url_slugs",
    "change_log",
    "staged_content",
)


class ModulestoreMigrationInline(admin.TabularInline):
    """
    Readonly table within the ModulestoreSource page; each row is a Migration from this Source.
    """
    model = ModulestoreMigration
    fk_name = "source"
    show_change_link = True
    readonly_fields = migration_admin_fields  # type: ignore[assignment]
    ordering = ("-task_status__created",)

    def has_add_permission(self, _request, _obj):
        return False


class ModulestoreBlockSourceInline(admin.TabularInline):
    """
    Readonly table within the ModulestoreSource page; each row is a BlockSource.
    """
    model = ModulestoreBlockSource
    fk_name = "overall_source"
    readonly_fields = (
        "key",
        "forwarded"
    )

    def has_add_permission(self, _request, _obj):
        return False


@admin.register(ModulestoreSource)
class ModulestoreSourceAdmin(admin.ModelAdmin):
    """
    Admin interface for source legacy libraries and courses.
    """
    readonly_fields = ("forwarded",)
    list_display = ("id", "key", "forwarded")
    actions = ["start_migration_task"]
    action_form = StartMigrationTaskForm
    inlines = [ModulestoreMigrationInline, ModulestoreBlockSourceInline]

    @admin.action(description="Start migration for selected sources")
    def start_migration_task(
        self,
        request: AuthenticatedHttpRequest,
        queryset: models.QuerySet[ModulestoreSource],
    ) -> None:
        """
        Start a migration for each selected source
        """
        form = StartMigrationTaskForm(request.POST)
        form.is_valid()
        target_key_string = form.cleaned_data['target_key']
        if not target_key_string:
            messages.add_message(request, messages.ERROR, "Target key is required")
            return
        try:
            target_library_key = LibraryLocatorV2.from_string(target_key_string)
            target_collection_slug = None
        except InvalidKeyError:
            try:
                target_collection_key = LibraryCollectionLocator.from_string(target_key_string)
                target_library_key = target_collection_key.lib_key
                target_collection_slug = target_collection_key.collection_id
            except InvalidKeyError:
                messages.add_message(request, messages.ERROR, f"Invalid target key: {target_key_string}")
                return
        started = 0
        total = 0
        for source in queryset:
            total += 1
            try:
                api.start_migration_to_library(
                    user=request.user,
                    source_key=source.key,
                    target_library_key=target_library_key,
                    target_collection_slug=target_collection_slug,
                    composition_level=CompositionLevel(form.cleaned_data['composition_level']),
                    repeat_handling_strategy=RepeatHandlingStrategy(form.cleaned_data['repeat_handling_strategy']),
                    preserve_url_slugs=form.cleaned_data['preserve_url_slugs'],
                    forward_source_to_target=form.cleaned_data['forward_to_target'],
                )
            except Exception as exc:  # pylint: disable=broad-except
                message = f"Failed to start migration {source.key} -> {target_key_string}"
                messages.add_message(request, messages.ERROR, f"{message}: {exc}")
                log.exception(message)
                continue
            started += 1
        click_in = "Click into the source objects to see migration details."

        if not started:
            messages.add_message(request, messages.WARNING, f"Failed to start {total} migration(s).")
        if started < total:
            messages.add_message(request, messages.WARNING, f"Started {started} of {total} migration(s). {click_in}")
        else:
            messages.add_message(request, messages.INFO, f"Started {started} migration(s). {click_in}")


class ModulestoreBlockMigrationInline(admin.TabularInline):
    """
    Readonly table witin the Migration admin; each row is a block
    """
    model = ModulestoreBlockMigration
    fk_name = "overall_migration"
    readonly_fields = (
        "source",
        "target",
        "change_log_record",
        "unsupported_reason",
    )
    list_display = ("id", *readonly_fields)


@admin.register(ModulestoreMigration)
class ModulestoreMigrationAdmin(admin.ModelAdmin):
    """
    Readonly admin page for viewing Migrations
    """
    readonly_fields = ("source", *migration_admin_fields)  # type: ignore[assignment]
    list_display = ("id", "source", *migration_admin_fields)  # type: ignore[assignment]
    inlines = [ModulestoreBlockMigrationInline]