use std::collections::HashMap;

use askama::Template;
use axum::{
    debug_handler,
    extract::{Path, State},
    response::{Html, IntoResponse},
};
use interim_models::{
    field::Field,
    field_form_prompt::FieldFormPrompt,
    form_transition::FormTransition,
    language::Language,
    portal::Portal,
    workspace::Workspace,
    workspace_user_perm::{self, WorkspaceUserPerm},
};
use interim_pgtypes::pg_attribute::PgAttribute;
use serde::{Deserialize, Serialize};
use sqlx::postgres::types::Oid;
use strum::IntoEnumIterator as _;
use uuid::Uuid;

use crate::{
    app::{App, AppDbConn},
    errors::{AppError, forbidden},
    field_info::FormFieldInfo,
    navigator::{Navigator, NavigatorPage as _},
    settings::Settings,
    user::CurrentUser,
    workspace_nav::{NavLocation, RelLocation, WorkspaceNav},
    workspace_pooler::{RoleAssignment, WorkspacePooler},
    workspace_utils::{RelationPortalSet, fetch_all_accessible_portals},
};

#[derive(Debug, Deserialize)]
pub(super) struct PathParams {
    portal_id: Uuid,
    rel_oid: u32,
    workspace_id: Uuid,
}

/// HTTP GET handler for the top-level portal form builder page.
#[debug_handler(state = App)]
pub(super) async fn get(
    State(settings): State<Settings>,
    CurrentUser(user): CurrentUser,
    AppDbConn(mut app_db): AppDbConn,
    Path(PathParams {
        portal_id,
        rel_oid,
        workspace_id,
    }): Path<PathParams>,
    navigator: Navigator,
    State(mut pooler): State<WorkspacePooler>,
) -> Result<impl IntoResponse, AppError> {
    // Check workspace authorization.
    let workspace_perms = WorkspaceUserPerm::belonging_to_user(user.id)
        .fetch_all(&mut app_db)
        .await?;
    if workspace_perms.iter().all(|p| {
        p.workspace_id != workspace_id || p.perm != workspace_user_perm::PermissionValue::Connect
    }) {
        return Err(forbidden!("access denied to workspace"));
    }
    // FIXME ensure workspace corresponds to rel/portal, and that user has
    // permission to access/alter both as needed.

    let portal = Portal::with_id(portal_id).fetch_one(&mut app_db).await?;
    let workspace = Workspace::with_id(portal.workspace_id)
        .fetch_one(&mut app_db)
        .await?;

    let mut workspace_client = pooler
        .acquire_for(workspace.id, RoleAssignment::User(user.id))
        .await?;

    let attrs: HashMap<String, PgAttribute> = PgAttribute::all_for_rel(portal.class_oid)
        .fetch_all(&mut workspace_client)
        .await?
        .into_iter()
        .map(|attr| (attr.attname.clone(), attr))
        .collect();
    let fields: Vec<FormFieldInfo> = {
        let fields: Vec<Field> = Field::belonging_to_portal(portal.id)
            .fetch_all(&mut app_db)
            .await?;
        let mut field_info: Vec<FormFieldInfo> = Vec::with_capacity(fields.len());
        for field in fields {
            let attr = attrs.get(&field.name);
            let prompts: HashMap<Language, String> = FieldFormPrompt::belonging_to_field(field.id)
                .fetch_all(&mut app_db)
                .await?
                .into_iter()
                .map(|value| (value.language, value.content))
                .collect();
            field_info.push(FormFieldInfo {
                field,
                column_present: attr.is_some(),
                has_default: attr.map(|value| value.atthasdef).unwrap_or(false),
                not_null: attr.and_then(|value| value.attnotnull).unwrap_or_default(),
                prompts,
            });
        }
        field_info
    };

    // FIXME: exclude portals user does not have access to, as well as
    // unnecessary fields
    let portal_sets =
        fetch_all_accessible_portals(workspace_id, &mut app_db, &mut workspace_client).await?;

    #[derive(Template)]
    #[template(path = "relations_single/form_index.html")]
    struct ResponseTemplate {
        fields: Vec<FormFieldInfo>,
        identifier_hints: Vec<String>,
        languages: Vec<LanguageInfo>,
        navigator: Navigator,
        portal: Portal,
        portals: Vec<PortalDisplay>,
        settings: Settings,
        transitions: Vec<FormTransition>,
        workspace_nav: WorkspaceNav,
    }
    #[derive(Debug, Serialize)]
    struct LanguageInfo {
        code: String,
        locale_str: String,
    }
    #[derive(Debug, Serialize)]
    struct PortalDisplay {
        id: Uuid,
        display_name: String,
    }
    Ok(Html(
        ResponseTemplate {
            fields,
            identifier_hints: attrs.keys().cloned().collect(),
            languages: Language::iter()
                .map(|value| LanguageInfo {
                    code: value.to_string(),
                    locale_str: value.as_locale_str().to_owned(),
                })
                .collect(),
            portal,
            portals: portal_sets
                .iter()
                .flat_map(|RelationPortalSet { rel, portals }| {
                    portals.iter().map(|portal| PortalDisplay {
                        id: portal.id,
                        display_name: format!(
                            "{rel_name}: {portal_name}",
                            rel_name = rel.relname,
                            portal_name = portal.name
                        ),
                    })
                })
                .collect(),
            transitions: FormTransition::with_source(portal_id)
                .fetch_all(&mut app_db)
                .await?,
            workspace_nav: WorkspaceNav::builder()
                .navigator(navigator.clone())
                .workspace(workspace)
                .populate_rels(&mut app_db, &mut workspace_client)
                .await?
                .current(NavLocation::Rel(
                    Oid(rel_oid),
                    Some(RelLocation::Portal(portal_id)),
                ))
                .build()?,
            navigator,
            settings,
        }
        .render()?,
    ))
}