from __future__ import annotations

import json
from typing import Iterable, Optional, Tuple

from django import urls
from django.contrib import admin
from django.db.models import QuerySet
from django.http import HttpRequest
from django.utils.html import SafeString, format_html

from .models import (
    BotSetting,
    DeletedMessage,
    DocumentationLink,
    Infraction,
    LogEntry,
    MessageDeletionContext,
    Nomination,
    OffTopicChannelName,
    OffensiveMessage,
    Role,
    User
)


@admin.register(LogEntry)
class LogEntryAdmin(admin.ModelAdmin):
    """Allows viewing logs in the Django Admin without allowing edits."""

    actions = None
    list_display = ('timestamp', 'application', 'level', 'message')
    fieldsets = (
        ('Overview', {'fields': ('timestamp', 'application', 'logger_name')}),
        ('Metadata', {'fields': ('level', 'module', 'line')}),
        ('Contents', {'fields': ('message',)})
    )
    list_filter = ('application', 'level', 'timestamp')
    search_fields = ('message',)
    readonly_fields = (
        'application',
        'logger_name',
        'timestamp',
        'level',
        'module',
        'line',
        'message'
    )

    def has_add_permission(self, request: HttpRequest) -> bool:
        """Deny manual LogEntry creation."""
        return False

    def has_delete_permission(self, request: HttpRequest, obj: Optional[LogEntry] = None) -> bool:
        """Deny LogEntry deletion."""
        return False


@admin.register(DeletedMessage)
class DeletedMessageAdmin(admin.ModelAdmin):
    """Admin formatting for the DeletedMessage model."""

    readonly_fields = (
        "id",
        "author",
        "channel_id",
        "content",
        "embed_data",
        "context",
        "view_full_log"
    )

    exclude = ("embeds", "deletion_context")

    search_fields = (
        "id",
        "content",
        "author__name",
        "author__id",
        "deletion_context__actor__name",
        "deletion_context__actor__id"
    )

    @staticmethod
    def embed_data(instance: DeletedMessage) -> Optional[str]:
        """Format embed data in a code block for better readability."""
        if instance.embeds:
            return format_html(
                "<pre style='word-wrap: break-word; white-space: pre-wrap; overflow-x: auto;'>"
                "<code>{0}</code></pre>",
                json.dumps(instance.embeds, indent=4)
            )

    @staticmethod
    def context(instance: DeletedMessage) -> str:
        """Provide full context info with a link through to context admin view."""
        link = urls.reverse(
            "admin:api_messagedeletioncontext_change",
            args=[instance.deletion_context.id]
        )
        details = (
            f"Deleted by {instance.deletion_context.actor} at "
            f"{instance.deletion_context.creation}"
        )
        return format_html("<a href='{0}'>{1}</a>", link, details)

    @staticmethod
    def view_full_log(instance: DeletedMessage) -> str:
        """Provide a link to the message logs for the relevant context."""
        return format_html(
            "<a href='{0}'>Click to view full context log</a>",
            instance.deletion_context.log_url
        )


@admin.register(MessageDeletionContext)
class MessageDeletionContextAdmin(admin.ModelAdmin):
    """Admin formatting for the MessageDeletionContext model."""

    readonly_fields = ("actor", "creation", "message_log")

    @staticmethod
    def message_log(instance: MessageDeletionContext) -> str:
        """Provide a formatted link to the message logs for the context."""
        return format_html(
            "<a href='{0}'>Click to see deleted message log</a>",
            instance.log_url
        )


@admin.register(Infraction)
class InfractionAdmin(admin.ModelAdmin):
    """Admin formatting for the Infraction model."""

    fields = (
        "user",
        "actor",
        "type",
        "reason",
        "inserted_at",
        "expires_at",
        "active",
        "hidden"
    )
    readonly_fields = (
        "user",
        "actor",
        "type",
        "inserted_at"
    )
    list_display = (
        "type",
        "user",
        "actor",
        "inserted_at",
        "expires_at",
        "reason",
        "active",
    )
    search_fields = (
        "id",
        "user__name",
        "user__id",
        "actor__name",
        "actor__id",
        "reason",
        "type"
    )
    list_filter = (
        "type",
        "hidden",
        "active"
    )


@admin.register(Nomination)
class NominationAdmin(admin.ModelAdmin):
    """Admin formatting for the Nomination model."""

    list_display = (
        "user",
        "active",
        "reason",
        "actor",
        "inserted_at",
        "ended_at"
    )
    fields = (
        "user",
        "active",
        "actor",
        "reason",
        "inserted_at",
        "ended_at",
        "end_reason"
    )
    readonly_fields = (
        "user",
        "active",
        "actor",
        "inserted_at",
        "ended_at"
    )
    search_fields = (
        "actor__name",
        "actor__id",
        "user__name",
        "user__id",
        "reason"
    )
    list_filter = ("active",)


@admin.register(OffTopicChannelName)
class OffTopicChannelNameAdmin(admin.ModelAdmin):
    """Admin formatting for the OffTopicChannelName model."""

    search_fields = ("name",)


@admin.register(Role)
class RoleAdmin(admin.ModelAdmin):
    """Admin formatting for the Role model."""

    exclude = ("permissions", "colour")
    readonly_fields = (
        "name",
        "id",
        "colour_with_preview",
        "permissions_with_calc_link",
        "position"
    )
    search_fields = ("name", "id")

    def colour_with_preview(self, instance: Role) -> str:
        """Show colour value in both int and hex, in bolded and coloured style."""
        return format_html(
            "<span style='color: #{0}!important; font-weight: bold;'>{1} / #{0}</span>",
            f"{instance.colour:06x}",
            instance.colour
        )

    def permissions_with_calc_link(self, instance: Role) -> str:
        """Show permissions with link to API permissions calculator page."""
        return format_html(
            "<a href='https://discordapi.com/permissions.html#{0}' target='_blank'>{0}</a>",
            instance.permissions
        )

    colour_with_preview.short_description = "Colour"
    permissions_with_calc_link.short_description = "Permissions"


class UserTopRoleFilter(admin.SimpleListFilter):
    """List Filter for User list Admin page."""

    title = "Role"
    parameter_name = "role"

    def lookups(self, request: HttpRequest, model_admin: UserAdmin) -> Iterable[Tuple[str, str]]:
        """Selectable values for viewer to filter by."""
        roles = Role.objects.all()
        return ((r.name, r.name) for r in roles)

    def queryset(self, request: HttpRequest, queryset: QuerySet) -> Optional[QuerySet]:
        """Query to filter the list of Users against."""
        if not self.value():
            return
        role = Role.objects.get(name=self.value())
        return queryset.filter(roles__contains=[role.id])


@admin.register(User)
class UserAdmin(admin.ModelAdmin):
    """Admin formatting for the User model."""

    def top_role_coloured(self, user: User) -> SafeString:
        """Returns the top role of the user with html style matching role colour."""
        return format_html(
            '<span style="color: #{0:06X}; font-weight: bold;">{1}</span>',
            user.top_role.colour,
            user.top_role.name
        )

    top_role_coloured.short_description = "Top Role"

    def all_roles_coloured(self, user: User) -> SafeString:
        """Returns all user roles with html style matching role colours."""
        roles = Role.objects.filter(id__in=user.roles)
        return format_html(
            "</br>".join(
                f'<span style="color: #{r.colour:06X}; font-weight: bold;">{r.name}</span>'
                for r in roles
            )
        )

    all_roles_coloured.short_description = "All Roles"

    search_fields = ("name", "id", "roles")
    list_filter = (UserTopRoleFilter, "in_guild")
    list_display = ("username", "top_role_coloured", "in_guild")
    fields = ("username", "id", "in_guild", "all_roles_coloured")
    sortable_by = ("username",)

    def has_add_permission(self, *args) -> bool:
        """Prevent adding from django admin."""
        return False

    def has_change_permission(self, *args) -> bool:
        """Prevent editing from django admin."""
        return False


admin.site.register(BotSetting)
admin.site.register(DocumentationLink)
admin.site.register(OffensiveMessage)