use std::collections::HashMap;

use axum::{
    Json, debug_handler,
    extract::{Path, State},
    response::{IntoResponse as _, Response},
};
use phono_backends::{
    escape_identifier, pg_acl::PgPrivilegeType, pg_attribute::PgAttribute, pg_class::PgClass,
};
use phono_models::{
    accessors::{Accessor, Actor, portal::PortalAccessor},
    datum::Datum,
};
use serde::Deserialize;
use serde_json::json;
use sqlx::{Acquire as _, postgres::types::Oid, query};
use uuid::Uuid;

use crate::{
    app::{App, AppDbConn},
    errors::{AppError, forbidden},
    user::CurrentUser,
    workspace_pooler::{RoleAssignment, WorkspacePooler},
};

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

#[derive(Debug, Deserialize)]
pub(super) struct FormBody {
    cells: Vec<CellInfo>,
}

#[derive(Debug, Deserialize)]
pub(super) struct CellInfo {
    column: String,
    pkey: HashMap<String, Datum>,
    value: Datum,
}

/// HTTP POST handler for updating cell values in a backing Postgres table.
///
/// This handler expects 3 path parameters with the structure described by
/// [`PathParams`].
#[debug_handler(state = App)]
pub(super) async fn post(
    State(mut workspace_pooler): State<WorkspacePooler>,
    AppDbConn(mut app_db): AppDbConn,
    CurrentUser(user): CurrentUser,
    Path(PathParams {
        portal_id,
        rel_oid,
        workspace_id,
    }): Path<PathParams>,
    Json(form): Json<FormBody>,
) -> Result<Response, AppError> {
    // Prevent users from modifying Phonograph metadata columns.
    if form.cells.iter().any(|cell| cell.column.starts_with('_')) {
        return Err(forbidden!("access denied to update system metadata column"));
    }

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

    let rel = PgClass::with_oid(Oid(rel_oid))
        .fetch_one(&mut workspace_client)
        .await?;

    // For authorization only.
    let _portal = PortalAccessor::new()
        .id(portal_id)
        .as_actor(Actor::User(user.id))
        .verify_workspace_id(workspace_id)
        .verify_rel_oid(Oid(rel_oid))
        .verify_rel_permissions([PgPrivilegeType::Update])
        .using_rel(&rel)
        .using_app_db(&mut app_db)
        .using_workspace_client(&mut workspace_client)
        .fetch_one()
        .await?;

    let pkey_attrs = PgAttribute::pkeys_for_rel(Oid(rel_oid))
        .fetch_all(&mut workspace_client)
        .await?;

    let conn = workspace_client.get_conn();
    let mut txn = conn.begin().await?;
    for cell in form.cells {
        // TODO: simplify pkey management
        cell.pkey
            .get(&pkey_attrs.first().unwrap().attname)
            .unwrap()
            .clone()
            .bind_onto(cell.value.bind_onto(query(&format!(
                "update {ident} set {value_col} = $1 where {pkey_col} = $2",
                ident = rel.get_identifier(),
                value_col = escape_identifier(&cell.column),
                pkey_col = escape_identifier(&pkey_attrs.first().unwrap().attname),
            ))))
            .execute(&mut *txn)
            .await?;
    }
    txn.commit().await?;

    Ok(Json(json!({ "ok": true })).into_response())
}