//! Reservations.
//!
//! Filing a request only needs a session — the requester is taken from it, never
//! from the body. Reading the whole list is an admin action for now; changing a status is
//! reserved to the unit the reservation belongs to (an admin manages every
//! unit), which is why the handler resolves the unit before narrowing the
//! controller down.

use aide::{
    axum::{
        ApiRouter,
        routing::{get_with, put_with},
    },
    transform::TransformOperation,
};
use axum::{Json, extract::Path, http::StatusCode};
use chrono::{DateTime, Utc};
use schemars::JsonSchema;
use serde::Deserialize;

use crate::{
    api::helpers::{IdPath, admin, admin_desc, desc, manager, manager_desc, unexpected_error},
    core::{
        controller::{
            AnonAppController, AppController, ControllerError,
            reservations::ReservationsControllerError,
        },
        models::{
            bike::BikeId,
            reservation::{
                CalendarReservation, NewReservation, Reservation, ReservationEdit,
                ReservationStatus,
            },
        },
    },
};

pub fn routes() -> ApiRouter {
    ApiRouter::new()
        .api_route(
            "/",
            get_with(get_reservations, get_reservations_docs)
                .post_with(create_reservation, create_reservation_docs),
        )
        // Before `/{id}`, which would otherwise be a candidate for these
        .api_route(
            "/mine",
            get_with(get_my_reservations, get_my_reservations_docs),
        )
        .api_route(
            "/calendar",
            get_with(get_calendar_reservations, get_calendar_reservations_docs),
        )
        .api_route(
            "/{id}",
            put_with(update_reservation, update_reservation_docs),
        )
        .api_route("/{id}/status", put_with(set_status, set_status_docs))
}

#[axum::debug_handler]
async fn get_reservations(
    ac: AppController,
) -> Result<Json<Vec<Reservation>>, (StatusCode, String)> {
    match admin(ac)?.get_reservations().await {
        Ok(reservations) => Ok(Json(reservations)),
        Err(err) => unexpected_error("get_reservations", err),
    }
}

fn get_reservations_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("Get every reservation")
        .response_with::<403, (), _>(admin_desc)
}

/// Files a request. The reservation always starts in `requested`: the status is
/// not part of the body, so a requester cannot approve their own booking.
#[axum::debug_handler]
async fn create_reservation(
    ac: AppController,
    Json(reservation): Json<NewReservation>,
) -> Result<(StatusCode, Json<Reservation>), (StatusCode, String)> {
    match ac.create_reservation(reservation).await {
        Ok(reservation) => Ok((StatusCode::CREATED, Json(reservation))),
        Err(ControllerError::Reservation(
            err @ ReservationsControllerError::ReservationInvalid,
        )) => Err((StatusCode::BAD_REQUEST, err.to_string())),
        Err(ControllerError::Reservation(
            err @ ReservationsControllerError::BikeOutOfService(_),
        )) => Err((StatusCode::CONFLICT, err.to_string())),
        Err(ControllerError::Reservation(
            err @ ReservationsControllerError::NotAMemberOfUnit(_),
        )) => Err((StatusCode::FORBIDDEN, err.to_string())),
        // An unknown unit id or bike id: the client named something that is gone
        Err(err) if err.is_not_found() => Err((
            StatusCode::UNPROCESSABLE_ENTITY,
            "Unknown unit or bike".to_owned(),
        )),
        Err(err) => unexpected_error("create_reservation", err),
    }
}

fn create_reservation_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("File a reservation request")
        .description(
            "The requester is the session user and the status starts at `requested`; \
             neither is taken from the body.",
        )
        .response_with::<201, Json<Reservation>, _>(desc("The reservation, as stored"))
        .response_with::<400, (), _>(desc("The reservation is malformed"))
        .response_with::<403, (), _>(desc("The requester does not belong to the unit named"))
        .response_with::<409, (), _>(desc("One of the bikes is out of service"))
        .response_with::<422, (), _>(desc("The unit or one of the bikes does not exist"))
}

/// The availability calendar, open to everybody: when the bikes are taken and by
/// which association, with nothing personal attached.
#[axum::debug_handler]
async fn get_calendar_reservations(
    aac: AnonAppController,
) -> Result<Json<Vec<CalendarReservation>>, (StatusCode, String)> {
    match aac.get_calendar_reservations().await {
        Ok(reservations) => Ok(Json(reservations)),
        Err(err) => unexpected_error("get_calendar_reservations", err),
    }
}

fn get_calendar_reservations_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("Get the approved and ongoing reservations, for the public calendar")
        .description(
            "No session needed, and no personal field travels: the telegram handle, \
             the people, the Linka Go addresses and the reason are left out.",
        )
}

/// Everything the session user is part of: what they filed, what they were
/// added to, and what lists their address among the Linka Go accounts.
#[axum::debug_handler]
async fn get_my_reservations(
    ac: AppController,
) -> Result<Json<Vec<Reservation>>, (StatusCode, String)> {
    match ac.get_my_reservations().await {
        Ok(reservations) => Ok(Json(reservations)),
        Err(err) => unexpected_error("get_my_reservations", err),
    }
}

fn get_my_reservations_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("Get the reservations the session user is part of")
        .description(
            "An address listed among the Linka Go accounts is enough, which is how \
             somebody added before they ever logged in finds the reservation waiting \
             for them.",
        )
}

/// Only what the admin page lets somebody change. The unit, the requester, the
/// telegram handle and the reason are shown but not editable, so they are not
/// in the body at all: the handler reads them back from the stored reservation
/// rather than trusting a client to send them unchanged.
#[derive(Debug, Deserialize, JsonSchema)]
struct ReservationEditForm {
    start_time: DateTime<Utc>,
    end_time: DateTime<Utc>,
    bikes: Vec<BikeId>,
    linka_emails: Vec<String>,
}

#[axum::debug_handler]
async fn update_reservation(
    ac: AppController,
    Path(IdPath { id }): Path<IdPath>,
    Json(form): Json<ReservationEditForm>,
) -> Result<(), (StatusCode, String)> {
    let current = match ac.get_reservation(id).await {
        Ok(reservation) => reservation,
        Err(err) if err.is_not_found() => {
            return Err((StatusCode::NOT_FOUND, "No such reservation".to_owned()));
        }
        Err(err) => return unexpected_error("update_reservation", err),
    };

    let edit = ReservationEdit {
        id,
        unit: current.unit.as_new(),
        start_time: form.start_time,
        end_time: form.end_time,
        users: current.users.iter().map(|user| user.id).collect(),
        telegram: current.telegram,
        description: current.description,
        bikes: form.bikes,
        linka_emails: form.linka_emails,
    };

    match ac.update_reservation(edit).await {
        Ok(()) => Ok(()),
        Err(ControllerError::Reservation(
            err @ ReservationsControllerError::ReservationInvalid,
        )) => Err((StatusCode::BAD_REQUEST, err.to_string())),
        Err(ControllerError::Reservation(
            err @ (ReservationsControllerError::BikeOutOfService(_)
            | ReservationsControllerError::ReservationFinal(_)),
        )) => Err((StatusCode::CONFLICT, err.to_string())),
        Err(ControllerError::Reservation(
            err @ (ReservationsControllerError::NotOnTheReservation
            | ReservationsControllerError::OnlyEmailsEditable(_)),
        )) => Err((StatusCode::FORBIDDEN, err.to_string())),
        Err(err) if err.is_not_found() => {
            Err((StatusCode::UNPROCESSABLE_ENTITY, "Unknown bike".to_owned()))
        }
        Err(err) => unexpected_error("update_reservation", err),
    }
}

fn update_reservation_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("Edit the period, the bikes and the Linka Go accounts")
        .description(
            "Everything else is left as stored. A manager may change all three until \
             the reservation is final; anybody else on it may do so only while it is \
             still a request, and afterwards only the Linka Go accounts.",
        )
        .response_with::<403, (), _>(desc(
            "The user is not on the reservation, or tried to change more than the \
             Linka Go accounts on one that is already approved",
        ))
        .response::<404, ()>()
        .response_with::<400, (), _>(desc("The reservation would become malformed"))
        .response_with::<409, (), _>(desc(
            "A newly added bike is out of service, or the reservation is final",
        ))
        .response_with::<422, (), _>(desc("One of the bikes does not exist"))
}

#[derive(Debug, Deserialize, JsonSchema)]
struct SetStatusForm {
    status: ReservationStatus,
}

#[axum::debug_handler]
async fn set_status(
    ac: AppController,
    Path(IdPath { id }): Path<IdPath>,
    Json(SetStatusForm { status }): Json<SetStatusForm>,
) -> Result<(), (StatusCode, String)> {
    // The unit is not in the body: it is the reservation's own
    let reservation = match ac.get_reservation(id).await {
        Ok(reservation) => reservation,
        Err(err) if err.is_not_found() => {
            return Err((StatusCode::NOT_FOUND, "No such reservation".to_owned()));
        }
        Err(err) => return unexpected_error("set_status", err),
    };

    match manager(ac, reservation.unit.scope())?
        .set_reservation_status(id, status)
        .await
    {
        Ok(()) => Ok(()),
        Err(ControllerError::Reservation(
            err @ ReservationsControllerError::InvalidTransition(..),
        )) => Err((StatusCode::CONFLICT, err.to_string())),
        Err(err) => unexpected_error("set_status", err),
    }
}

fn set_status_docs(op: TransformOperation) -> TransformOperation {
    op.tag("Reservations")
        .summary("Move a reservation through its state machine")
        .description("Refuses a transition the state machine does not allow, with a 409.")
        .response_with::<403, (), _>(manager_desc)
        .response::<404, ()>()
        .response::<409, ()>()
}