use axum::{
    debug_handler,
    extract::{Path, State},
    response::Response,
};
// [`axum_extra`]'s form extractor is preferred:
// https://docs.rs/axum-extra/0.10.1/axum_extra/extract/struct.Form.html#differences-from-axumextractform
use axum_extra::extract::Form;
use interim_models::{
    field::Field,
    portal::Portal,
    presentation::{Presentation, RFC_3339_S, TextInputMode},
    workspace::Workspace,
    workspace_user_perm::{self, WorkspaceUserPerm},
};
use interim_pgtypes::{escape_identifier, pg_class::PgClass};
use serde::Deserialize;
use sqlx::query;
use uuid::Uuid;

use crate::{
    app::{App, AppDbConn},
    errors::{AppError, forbidden},
    navigator::Navigator,
    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 {
    name: String,
    label: String,
    presentation_tag: String,
    dropdown_allow_custom: Option<bool>,
    text_input_mode: Option<String>,
    timestamp_format: Option<String>,
}

/// HTTP POST handler for adding a [`Field`] to a [`Portal`]. If the field name
/// does not match a column in the backing database, a new column is created
/// with a compatible type.
///
/// 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,
    navigator: Navigator,
    Path(PathParams {
        portal_id,
        workspace_id,
        ..
    }): Path<PathParams>,
    Form(form): Form<FormBody>,
) -> Result<Response, 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 = workspace_pooler
        .acquire_for(workspace.id, RoleAssignment::User(user.id))
        .await?;

    let class = PgClass::with_oid(portal.class_oid)
        .fetch_one(&mut workspace_client)
        .await?;

    let presentation = try_presentation_from_form(&form)?;

    query(&format!(
        "alter table {ident} add column if not exists {col} {typ}",
        ident = class.get_identifier(),
        col = escape_identifier(&form.name),
        typ = presentation.attr_data_type_fragment(),
    ))
    .execute(workspace_client.get_conn())
    .await?;

    Field::insert()
        .portal_id(portal.id)
        .name(form.name)
        .table_label(if form.label.is_empty() {
            None
        } else {
            Some(form.label)
        })
        .presentation(presentation)
        .build()?
        .insert(&mut app_db)
        .await?;

    Ok(navigator.portal_page(&portal).redirect_to())
}

fn try_presentation_from_form(form: &FormBody) -> Result<Presentation, AppError> {
    // Parses the presentation tag into the correct enum variant, but without
    // meaningful inner value(s). Match arms should all use the
    // `MyVariant { .. }` pattern to pay attention to only the tag.
    let presentation_default = Presentation::try_from(form.presentation_tag.as_str())?;
    Ok(match presentation_default {
        Presentation::Array { .. } => todo!(),
        Presentation::Dropdown { .. } => Presentation::Dropdown { allow_custom: true },
        Presentation::Text { .. } => Presentation::Text {
            input_mode: form
                .text_input_mode
                .clone()
                .map(|value| TextInputMode::try_from(value.as_str()))
                .transpose()?
                .unwrap_or_default(),
        },
        Presentation::Timestamp { .. } => Presentation::Timestamp {
            format: form
                .timestamp_format
                .clone()
                .unwrap_or(RFC_3339_S.to_owned()),
        },
        Presentation::Uuid { .. } => Presentation::Uuid {},
    })
}