//! Module amendments — the modules a seed now declares, added to a document
//! that was born without them (ADR 0009).
//!
//! Yvv, 2026-10-30: the title of the document at level 4, the order of the
//! articles of each section at level 2. A new base gets them from the seed
//! (`modules` in the seed file). An existing base — production holds two
//! instances of the certification act, Monnaie libre and the test group — gets
//! them through an amendment listed here, built **from what the document holds
//! then**: its title as it reads, and the order each section reads in. Nothing
//! else is written: no article moves, no text changes, no vote is touched.
//!
//! Like the seed and inertia amendments, each document is decided once, at the
//! first start that knows the amendment, and the decision is kept in
//! `module_amendments` (applied with the codes created, refused and why, or
//! present) and in the logs. Applied where the document publishes, the
//! publication queue gets a row (`document.json` carries the modules).

use crate::AppState;
use crate::modules::{self, Levels};
use crate::seed::SeedDoc;
use crate::util;
use ld_engine::inertia::InertiaLevel;
use sqlx::SqliteConnection;

/// Modules to add to every document instantiated from a seed.
pub struct ModuleAmendment {
    /// Stable identifier: each document's decision is kept under it.
    pub id: &'static str,
    /// Slug of the seed document.
    pub doc: &'static str,
    /// The level of the title module: the seed's today, which must say so.
    pub title: u8,
    /// The level of the order modules: the seed's today, which must say so.
    pub order: u8,
    /// Reason given to the publication queue, and so to the commit of the texts.
    pub reason: &'static str,
}

pub const AMENDMENTS: &[ModuleAmendment] = &[ModuleAmendment {
    id: "2026-10-31-modules-titre-ordre",
    doc: "acte-engagement-certification",
    title: 4,
    order: 2,
    reason: "modules ajoutés : le titre du document, l'ordre des articles de chaque section",
}];

/// What the database says of the document.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct Facts {
    /// Its title in its source language.
    pub title: String,
    /// Modules it holds already, of either kind.
    pub modules: i64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Verdict {
    Apply,
    /// Born with its modules: nothing to do.
    Present,
    Refuse(&'static str),
}

/// The rule, apart from the database.
pub fn verdict(facts: Option<&Facts>) -> Verdict {
    let Some(f) = facts else { return Verdict::Refuse("no_document") };
    if f.modules > 0 {
        Verdict::Present
    } else if f.title.trim().is_empty() {
        Verdict::Refuse("no_title")
    } else {
        Verdict::Apply
    }
}

/// A decision taken at this start.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Outcome {
    pub amendment: &'static str,
    pub group: String,
    pub verdict: Verdict,
    pub created: Vec<String>,
}

/// Decides every amendment not yet decided, document by document.
pub async fn apply(state: &AppState, seeds: &[SeedDoc], list: &[ModuleAmendment]) -> anyhow::Result<Vec<Outcome>> {
    let mut out = Vec::new();
    for a in list {
        let Some(levels) = seed_says(seeds, a) else { continue };
        let docs: Vec<(String, String, Option<String>)> =
            sqlx::query_as("SELECT id, group_slug, publish_path FROM documents WHERE slug = ? ORDER BY group_slug")
                .bind(a.doc)
                .fetch_all(&state.db)
                .await?;
        for (doc_id, group, publish_path) in docs {
            let Some((v, created)) = decide(state, a, levels, &doc_id, publish_path.is_some()).await? else {
                continue;
            };
            match v {
                Verdict::Apply => tracing::info!(amendment = a.id, %group, created = ?created, "modules added"),
                Verdict::Present => tracing::info!(amendment = a.id, %group, "modules: already there"),
                Verdict::Refuse(why) => {
                    tracing::warn!(amendment = a.id, %group, reason = why, "modules refused: the document stays as it is")
                }
            }
            if v == Verdict::Apply && publish_path.is_some() {
                state.publish_wake.notify_one();
            }
            out.push(Outcome { amendment: a.id, group, verdict: v, created });
        }
    }
    Ok(out)
}

/// The seed must declare the modules at the levels the amendment gives: a seed
/// edited later never reaches a base by this way.
fn seed_says(seeds: &[SeedDoc], a: &ModuleAmendment) -> Option<Levels> {
    let levels = seeds.iter().find(|s| s.slug == a.doc).and_then(|s| s.modules.as_ref()).map(Levels::from);
    let wanted = Levels { title: InertiaLevel::new(a.title), order: InertiaLevel::new(a.order) };
    match levels {
        Some(l) if l == wanted && l.title.is_some() && l.order.is_some() => Some(l),
        _ => {
            tracing::error!(
                amendment = a.id,
                doc = a.doc,
                "module amendment: the seed does not declare these modules, nothing decided"
            );
            None
        }
    }
}

async fn facts(conn: &mut SqliteConnection, doc_id: &str) -> sqlx::Result<Option<Facts>> {
    let doc: Option<(String, String)> = sqlx::query_as("SELECT title, source_lang FROM documents WHERE id = ?")
        .bind(doc_id)
        .fetch_optional(&mut *conn)
        .await?;
    let Some((raw, src)) = doc else { return Ok(None) };
    let modules: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM units WHERE doc_id = ? AND kind <> 'article'")
        .bind(doc_id)
        .fetch_one(&mut *conn)
        .await?;
    Ok(Some(Facts { title: util::parse_lang(&raw).get(&src).cloned().unwrap_or_default(), modules }))
}

/// One document, in one transaction: `None` when it was decided at an earlier start.
async fn decide(
    state: &AppState,
    a: &ModuleAmendment,
    levels: Levels,
    doc_id: &str,
    publishes: bool,
) -> anyhow::Result<Option<(Verdict, Vec<String>)>> {
    let mut tx = state.db.begin().await?;
    let decided: i64 =
        sqlx::query_scalar("SELECT COUNT(*) FROM module_amendments WHERE amendment_id = ? AND doc_id = ?")
            .bind(a.id)
            .bind(doc_id)
            .fetch_one(&mut *tx)
            .await?;
    if decided > 0 {
        return Ok(None);
    }
    let found = facts(&mut tx, doc_id).await?;
    let v = verdict(found.as_ref());
    let now = util::now();
    let created = if v == Verdict::Apply { modules::create(&mut tx, doc_id, levels, &now).await? } else { Vec::new() };
    if v == Verdict::Apply && publishes {
        sqlx::query("INSERT INTO outbox (doc_id, reason, created_at, next_at) VALUES (?, ?, ?, ?)")
            .bind(doc_id)
            .bind(a.reason)
            .bind(&now)
            .bind(&now)
            .execute(&mut *tx)
            .await?;
    }
    let (outcome, reason) = match v {
        Verdict::Apply => ("applied", None),
        Verdict::Present => ("present", None),
        Verdict::Refuse(why) => ("refused", Some(why)),
    };
    sqlx::query(
        "INSERT INTO module_amendments (amendment_id, doc_id, outcome, reason, created, at) VALUES (?, ?, ?, ?, ?, ?)",
    )
    .bind(a.id)
    .bind(doc_id)
    .bind(outcome)
    .bind(reason)
    .bind((v == Verdict::Apply).then(|| serde_json::to_string(&created).unwrap_or_else(|_| "[]".into())))
    .bind(&now)
    .execute(&mut *tx)
    .await?;
    tx.commit().await?;
    Ok(Some((v, created)))
}

#[cfg(test)]
mod tests {
    use super::*;

    fn doc(title: &str, modules: i64) -> Facts {
        Facts { title: title.into(), modules }
    }

    #[test]
    fn a_document_without_modules_receives_them() {
        assert_eq!(verdict(Some(&doc("Acte d'engagement Certification", 0))), Verdict::Apply);
    }

    #[test]
    fn a_document_born_with_its_modules_is_left_as_it_is() {
        assert_eq!(verdict(Some(&doc("Acte", 9))), Verdict::Present);
        assert_eq!(verdict(Some(&doc("Acte", 1))), Verdict::Present, "never a second set");
    }

    #[test]
    fn nothing_without_a_document_or_a_title() {
        assert_eq!(verdict(None), Verdict::Refuse("no_document"));
        assert_eq!(verdict(Some(&doc("  ", 0))), Verdict::Refuse("no_title"));
    }
}