//! The messages of trustinWallet (2026-10-31, lot F, ADR 0010): a box in the
//! application, in the menu, with the number of unread messages — no mail.
//!
//! A message is about a subject (an objection, a typo fix, a ballot set aside —
//! ADR 0012) and carries the
//! gestures that subject asks of its recipient now — lift or reiterate,
//! validate or refuse — and its deadline. A message dealt with offers no
//! gesture any more. Its text is told by the interface, in the language of the
//! reader, from the subject. Each person reads their own messages only
//! (`trustin_access::reads_message`); acting on a subject marks one's messages
//! about it as read.

use crate::AppState;
use crate::auth::{IdentityRow, User};
use crate::error::{AppError, AppResult};
use crate::{ballots, docs, objections, typos, util};
use axum::Json;
use axum::extract::{Path, State};
use serde_json::{Value, json};

/// The most recent messages shown in the box.
const SHOWN: i64 = 100;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Topic {
    Objection,
    Typo,
    /// A ballot set aside: never seen on the chain in time, refused, or its *for*
    /// proven while an objection held the version back (ADR 0012).
    Ballot,
}

impl Topic {
    pub fn as_str(self) -> &'static str {
        match self {
            Self::Objection => "objection",
            Self::Typo => "typo",
            Self::Ballot => "ballot",
        }
    }
}

/// Puts a message in someone's box.
#[allow(clippy::too_many_arguments)]
pub async fn notify(
    state: &AppState,
    recipient: &str,
    doc_id: &str,
    topic: Topic,
    subject_id: &str,
    kind: &str,
    cycle: i64,
    due: Option<&str>,
) -> AppResult<()> {
    sqlx::query(
        "INSERT INTO messages (id, recipient_id, doc_id, topic, subject_id, kind, cycle, created_at, due_at)
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
    )
    .bind(util::id())
    .bind(recipient)
    .bind(doc_id)
    .bind(topic.as_str())
    .bind(subject_id)
    .bind(kind)
    .bind(cycle)
    .bind(state.clock.now())
    .bind(due)
    .execute(&state.db)
    .await?;
    Ok(())
}

/// The messages about a subject (of some kinds, or all) are dealt with: what became of it.
pub async fn close(
    state: &AppState,
    topic: Topic,
    subject_id: &str,
    kinds: Option<&[&str]>,
    outcome: &str,
) -> AppResult<()> {
    let now = state.clock.now();
    match kinds {
        None => {
            sqlx::query(
                "UPDATE messages SET done_at = ?, outcome = ? WHERE topic = ? AND subject_id = ? AND done_at IS NULL",
            )
            .bind(&now)
            .bind(outcome)
            .bind(topic.as_str())
            .bind(subject_id)
            .execute(&state.db)
            .await?;
        }
        Some(kinds) => {
            for kind in kinds {
                sqlx::query(
                    "UPDATE messages SET done_at = ?, outcome = ?
                     WHERE topic = ? AND subject_id = ? AND kind = ? AND done_at IS NULL",
                )
                .bind(&now)
                .bind(outcome)
                .bind(topic.as_str())
                .bind(subject_id)
                .bind(kind)
                .execute(&state.db)
                .await?;
            }
        }
    }
    Ok(())
}

/// Someone acted on a subject: their messages about it are read.
pub async fn read_subject(state: &AppState, recipient: &str, topic: Topic, subject_id: &str) -> AppResult<()> {
    sqlx::query(
        "UPDATE messages SET read_at = ? WHERE recipient_id = ? AND topic = ? AND subject_id = ? AND read_at IS NULL",
    )
    .bind(state.clock.now())
    .bind(recipient)
    .bind(topic.as_str())
    .bind(subject_id)
    .execute(&state.db)
    .await?;
    Ok(())
}

async fn unread_of(state: &AppState, recipient: &str) -> AppResult<i64> {
    Ok(sqlx::query_scalar("SELECT COUNT(*) FROM messages WHERE recipient_id = ? AND read_at IS NULL")
        .bind(recipient)
        .fetch_one(&state.db)
        .await?)
}

#[derive(sqlx::FromRow)]
struct MessageRow {
    id: String,
    recipient_id: String,
    doc_id: String,
    topic: String,
    subject_id: String,
    kind: String,
    cycle: i64,
    created_at: String,
    due_at: Option<String>,
    read_at: Option<String>,
    done_at: Option<String>,
    outcome: Option<String>,
}

#[derive(sqlx::FromRow)]
struct DocLine {
    group_slug: String,
    slug: String,
    title: String,
}

async fn view(state: &AppState, me: &IdentityRow, m: &MessageRow) -> AppResult<Option<Value>> {
    let doc = sqlx::query_as::<_, DocLine>("SELECT group_slug, slug, title FROM documents WHERE id = ?")
        .bind(&m.doc_id)
        .fetch_optional(&state.db)
        .await?;
    let Some(doc) = doc else { return Ok(None) };
    // A message tells what is in a group: shown only while its recipient opens it.
    if !docs::opens(state, me, &docs::load_group(state, &doc.group_slug).await?).await? {
        return Ok(None);
    }
    let (subject, gestures) = match m.topic.as_str() {
        "objection" => match objections::for_message(state, me, &m.subject_id, &m.kind, m.cycle).await? {
            Some((v, g)) => (json!({ "objection": v }), g),
            None => return Ok(None),
        },
        "typo" => match typos::for_message(state, me, &m.subject_id).await? {
            Some((v, g)) => (json!({ "typo": v }), g),
            None => return Ok(None),
        },
        "ballot" => match ballots::for_message(state, me, &m.subject_id).await? {
            Some(v) => (json!({ "ballot": v }), Vec::new()),
            None => return Ok(None),
        },
        _ => return Ok(None),
    };
    let mut out = json!({
        "id": m.id, "topic": m.topic, "kind": m.kind, "cycle": m.cycle, "createdAt": m.created_at,
        "dueAt": m.due_at, "read": m.read_at.is_some(), "done": m.done_at.is_some() || gestures.is_empty(),
        "outcome": m.outcome, "gestures": gestures,
        "doc": { "id": m.doc_id, "groupSlug": doc.group_slug, "slug": doc.slug, "title": util::parse_lang(&doc.title) },
    });
    if let (Some(o), Value::Object(s)) = (out.as_object_mut(), subject) {
        o.extend(s);
    }
    Ok(Some(out))
}

/// `GET /api/messages` — one's own box, newest first.
pub async fn list(State(state): State<AppState>, User(me): User) -> AppResult<Json<Value>> {
    let rows = sqlx::query_as::<_, MessageRow>(
        "SELECT id, recipient_id, doc_id, topic, subject_id, kind, cycle, created_at, due_at, read_at, done_at, outcome
           FROM messages WHERE recipient_id = ? ORDER BY created_at DESC, rowid DESC LIMIT ?",
    )
    .bind(&me.id)
    .bind(SHOWN)
    .fetch_all(&state.db)
    .await?;
    let mut out = Vec::with_capacity(rows.len());
    for m in &rows {
        if !trustin_access::reads_message(&me.to_identity(), &m.recipient_id) {
            continue;
        }
        if let Some(v) = view(&state, &me, m).await? {
            out.push(v);
        }
    }
    Ok(Json(json!({ "unread": unread_of(&state, &me.id).await?, "messages": out })))
}

/// `GET /api/messages/unread` — the number next to « Messages » in the menu.
pub async fn unread(State(state): State<AppState>, User(me): User) -> AppResult<Json<Value>> {
    Ok(Json(json!({ "unread": unread_of(&state, &me.id).await? })))
}

/// `POST /api/messages/{id}/read` — one's own message only (404 otherwise).
pub async fn read(State(state): State<AppState>, User(me): User, Path(id): Path<String>) -> AppResult<Json<Value>> {
    let recipient: String = sqlx::query_scalar("SELECT recipient_id FROM messages WHERE id = ?")
        .bind(&id)
        .fetch_optional(&state.db)
        .await?
        .ok_or(AppError::NotFound)?;
    if !trustin_access::reads_message(&me.to_identity(), &recipient) {
        return Err(AppError::NotFound);
    }
    sqlx::query("UPDATE messages SET read_at = ? WHERE id = ? AND read_at IS NULL")
        .bind(state.clock.now())
        .bind(&id)
        .execute(&state.db)
        .await?;
    Ok(Json(json!({ "unread": unread_of(&state, &me.id).await? })))
}

/// `POST /api/messages/read` — every message of one's box.
pub async fn read_all(State(state): State<AppState>, User(me): User) -> AppResult<Json<Value>> {
    sqlx::query("UPDATE messages SET read_at = ? WHERE recipient_id = ? AND read_at IS NULL")
        .bind(state.clock.now())
        .bind(&me.id)
        .execute(&state.db)
        .await?;
    Ok(Json(json!({ "unread": 0 })))
}