//! Reading: groups, tools, documents, previews.
//!
//! The state of a document is loaded once (`DocState`) and turned into the
//! engine's pure types; every number shown on screen comes from the engine.

use crate::AppState;
use crate::auth::{IdentityRow, User};
use crate::error::{AppError, AppResult};
use crate::util::{self, LangMap};
use axum::Json;
use axum::extract::{Path, Query, State};
use ld_engine::compose::{self, PreviewMode, ProposalKind, ProposalState, UnitState, VersionText};
use ld_engine::threshold::{Evaluation, InertiaPreset, Tally, evaluate};
use serde::{Deserialize, Serialize};
use serde_json::json;
use std::collections::{BTreeMap, HashMap, HashSet};
use trustin_access::{Group, GroupPolicy};

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct GroupRow {
    pub slug: String,
    pub name: String,
    pub parent: Option<String>,
    pub policy: String,
    pub hidden: bool,
    pub position: i64,
}

impl GroupRow {
    pub fn to_group(&self) -> Group {
        Group {
            slug: self.slug.clone(),
            name: self.name.clone(),
            parent: self.parent.clone(),
            policy: GroupPolicy::parse(&self.policy).unwrap_or(GroupPolicy::Managed),
            hidden: self.hidden,
        }
    }
}

pub async fn granted(state: &AppState, group: &str, identity: &str) -> AppResult<bool> {
    let n: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM memberships WHERE group_slug = ? AND identity_id = ?")
        .bind(group)
        .bind(identity)
        .fetch_one(&state.db)
        .await?;
    Ok(n > 0)
}

pub async fn load_group(state: &AppState, slug: &str) -> AppResult<GroupRow> {
    sqlx::query_as::<_, GroupRow>("SELECT slug, name, parent, policy, hidden, position FROM groups WHERE slug = ?")
        .bind(slug)
        .fetch_optional(&state.db)
        .await?
        .ok_or(AppError::NotFound)
}

/// 404 for a group one cannot see, 403 for one seen but not open.
pub async fn require_open(state: &AppState, user: &IdentityRow, group: &GroupRow) -> AppResult<()> {
    let id = user.to_identity();
    let g = group.to_group();
    let has = granted(state, &group.slug, &user.id).await?;
    if !trustin_access::sees(&id, &g, has) {
        return Err(AppError::NotFound);
    }
    if !trustin_access::opens(&id, &g, has) {
        return Err(AppError::Forbidden);
    }
    Ok(())
}

/// May this identity vote in the group (see `trustin_access::votes_in`)?
pub async fn may_vote(state: &AppState, user: &IdentityRow, group: &GroupRow) -> AppResult<bool> {
    let has = granted(state, &group.slug, &user.id).await?;
    Ok(trustin_access::votes_in(&user.to_identity(), &group.to_group(), has))
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
struct GroupView {
    slug: String,
    name: String,
    parent: Option<String>,
    policy: String,
    open: bool,
}

pub async fn groups(State(state): State<AppState>, User(user): User) -> AppResult<Json<serde_json::Value>> {
    let rows = sqlx::query_as::<_, GroupRow>(
        "SELECT slug, name, parent, policy, hidden, position FROM groups ORDER BY position",
    )
    .fetch_all(&state.db)
    .await?;
    let id = user.to_identity();
    let mut out = Vec::new();
    for row in rows {
        let has = granted(&state, &row.slug, &user.id).await?;
        let g = row.to_group();
        if trustin_access::sees(&id, &g, has) {
            out.push(GroupView {
                open: trustin_access::opens(&id, &g, has),
                slug: row.slug,
                name: row.name,
                parent: row.parent,
                policy: row.policy,
            });
        }
    }
    Ok(Json(json!({ "groups": out })))
}

#[derive(Serialize, sqlx::FromRow)]
#[serde(rename_all = "camelCase")]
struct DocListRow {
    id: String,
    slug: String,
    #[sqlx(rename = "title")]
    #[serde(skip)]
    title_raw: String,
    #[sqlx(rename = "summary")]
    #[serde(skip)]
    summary_raw: String,
    in_force: i64,
    open: i64,
}

/// The tools of a group. Only "Docs de référence" is active for now.
pub const TOOLS: [(&str, bool); 4] = [("decisions", false), ("docs", true), ("mandats", false), ("protocoles", false)];

pub async fn group(
    State(state): State<AppState>,
    User(user): User,
    Path(slug): Path<String>,
) -> AppResult<Json<serde_json::Value>> {
    let row = load_group(&state, &slug).await?;
    let id = user.to_identity();
    let has = granted(&state, &slug, &user.id).await?;
    let g = row.to_group();
    if !trustin_access::sees(&id, &g, has) {
        return Err(AppError::NotFound);
    }
    let open = trustin_access::opens(&id, &g, has);
    let docs = if open {
        sqlx::query_as::<_, DocListRow>(
            "SELECT d.id, d.slug, d.title, d.summary,
               (SELECT COUNT(*) FROM units u WHERE u.doc_id = d.id AND u.in_force_id IS NOT NULL) AS in_force,
               (SELECT COUNT(*) FROM proposals p JOIN units u ON u.id = p.unit_id
                  WHERE u.doc_id = d.id AND p.status = 'open') AS open
             FROM documents d WHERE d.group_slug = ? ORDER BY d.created_at",
        )
        .bind(&slug)
        .fetch_all(&state.db)
        .await?
        .into_iter()
        .map(|d| {
            json!({
                "id": d.id, "slug": d.slug,
                "title": util::parse_lang(&d.title_raw), "summary": util::parse_lang(&d.summary_raw),
                "inForce": d.in_force, "open": d.open,
            })
        })
        .collect::<Vec<_>>()
    } else {
        Vec::new()
    };
    let tools: Vec<_> = TOOLS.iter().map(|(key, active)| json!({ "key": key, "active": active })).collect();
    Ok(Json(json!({
        "group": { "slug": row.slug, "name": row.name, "parent": row.parent, "policy": row.policy, "open": open },
        "tools": tools,
        "docs": docs,
    })))
}

// ---------------------------------------------------------------------------
// Document state
// ---------------------------------------------------------------------------

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct DocRow {
    pub id: String,
    pub group_slug: String,
    pub slug: String,
    pub title: String,
    pub summary: String,
    pub source_lang: String,
    pub vote_floor: f64,
    pub publish_path: Option<String>,
}

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct UnitRow {
    pub id: String,
    pub code: String,
    pub section: Option<String>,
    pub position: f64,
    pub inertia: String,
    pub in_force_id: Option<String>,
}

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct ProposalRow {
    pub id: String,
    pub unit_id: String,
    pub kind: String,
    pub inertia_target: Option<String>,
    pub title: String,
    pub body: String,
    pub status: String,
    pub origin: String,
    pub label: Option<String>,
    pub author_id: Option<String>,
    pub author_name: Option<String>,
    pub revision: i64,
    pub created_at: String,
    pub updated_at: String,
    pub submitted_at: Option<String>,
    pub entered_at: Option<String>,
    pub confirmed_at: Option<String>,
}

pub const PROPOSAL_SELECT: &str =
    "SELECT p.id, p.unit_id, p.kind, p.inertia_target, p.title, p.body, p.status, p.origin,
    p.label, p.author_id, i.display_name AS author_name, p.revision, p.created_at, p.updated_at, p.submitted_at,
    p.entered_at, p.confirmed_at
  FROM proposals p LEFT JOIN identities i ON i.id = p.author_id";

impl ProposalRow {
    pub fn kind(&self) -> ProposalKind {
        match self.kind.as_str() {
            "remove" => ProposalKind::Remove,
            "inertia" => ProposalKind::Inertia(
                self.inertia_target.as_deref().and_then(InertiaPreset::parse).unwrap_or(InertiaPreset::Standard),
            ),
            _ => ProposalKind::Text,
        }
    }
}

pub fn inertia_of(unit: &UnitRow) -> InertiaPreset {
    InertiaPreset::parse(&unit.inertia).unwrap_or(InertiaPreset::Standard)
}

pub struct DocState {
    pub doc: DocRow,
    pub group: GroupRow,
    pub units: Vec<UnitRow>,
    pub proposals: Vec<ProposalRow>,
    pub tallies: HashMap<String, Tally>,
    pub blocked: HashSet<String>,
    pub signal_counts: HashMap<String, i64>,
    pub electorate: u32,
    pub electorate_source: &'static str,
}

pub async fn load_doc(state: &AppState, doc_id: &str) -> AppResult<DocRow> {
    sqlx::query_as::<_, DocRow>(
        "SELECT id, group_slug, slug, title, summary, source_lang, vote_floor, publish_path FROM documents WHERE id = ?",
    )
    .bind(doc_id)
    .fetch_optional(&state.db)
    .await?
    .ok_or(AppError::NotFound)
}

/// W: the Ğ1 web of trust for Monnaie libre, the members of the group otherwise.
pub async fn electorate(state: &AppState, group: &GroupRow) -> AppResult<(u32, &'static str)> {
    if group.policy == GroupPolicy::G1Members.as_str() {
        let cached: Option<String> =
            sqlx::query_scalar("SELECT value FROM settings WHERE key = 'wot_size'").fetch_optional(&state.db).await?;
        let w = cached.and_then(|v| v.parse().ok()).unwrap_or(state.cfg.wot_fallback);
        return Ok((w.max(1), "wot"));
    }
    let n: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM memberships WHERE group_slug = ?")
        .bind(&group.slug)
        .fetch_one(&state.db)
        .await?;
    Ok((u32::try_from(n).unwrap_or(u32::MAX).max(1), "group"))
}

pub async fn load_state(state: &AppState, doc_id: &str) -> AppResult<DocState> {
    let doc = load_doc(state, doc_id).await?;
    let group = load_group(state, &doc.group_slug).await?;
    let units = sqlx::query_as::<_, UnitRow>(
        "SELECT id, code, section, position, inertia, in_force_id FROM units WHERE doc_id = ? ORDER BY position, id",
    )
    .bind(doc_id)
    .fetch_all(&state.db)
    .await?;
    let proposals = sqlx::query_as::<_, ProposalRow>(&format!(
        "{PROPOSAL_SELECT} WHERE p.unit_id IN (SELECT id FROM units WHERE doc_id = ?)
           AND p.status IN ('open', 'in_force', 'draft') ORDER BY p.submitted_at, p.created_at, p.id"
    ))
    .bind(doc_id)
    .fetch_all(&state.db)
    .await?;

    #[derive(sqlx::FromRow)]
    struct TallyRow {
        proposal_id: String,
        choice: String,
        n: i64,
    }
    let rows = sqlx::query_as::<_, TallyRow>(
        "SELECT v.proposal_id, v.choice, COUNT(*) AS n FROM votes v JOIN proposals p ON p.id = v.proposal_id
         JOIN units u ON u.id = p.unit_id
         WHERE u.doc_id = ? AND v.revision = p.revision GROUP BY v.proposal_id, v.choice",
    )
    .bind(doc_id)
    .fetch_all(&state.db)
    .await?;
    let mut tallies: HashMap<String, Tally> = HashMap::new();
    for r in rows {
        let t = tallies.entry(r.proposal_id).or_default();
        let n = u32::try_from(r.n).unwrap_or(0);
        match r.choice.as_str() {
            "for" => t.for_votes = n,
            "against" => t.against = n,
            _ => {}
        }
    }

    #[derive(sqlx::FromRow)]
    struct SignalRow {
        proposal_id: String,
        target_proposal_id: String,
    }
    let signals = sqlx::query_as::<_, SignalRow>(
        "SELECT s.proposal_id, s.target_proposal_id FROM signals s JOIN proposals p ON p.id = s.proposal_id
         JOIN units u ON u.id = p.unit_id WHERE u.doc_id = ? AND s.lifted_at IS NULL",
    )
    .bind(doc_id)
    .fetch_all(&state.db)
    .await?;
    let in_force: HashSet<&str> = units.iter().filter_map(|u| u.in_force_id.as_deref()).collect();
    let mut blocked = HashSet::new();
    let mut signal_counts: HashMap<String, i64> = HashMap::new();
    for s in &signals {
        *signal_counts.entry(s.proposal_id.clone()).or_default() += 1;
        *signal_counts.entry(s.target_proposal_id.clone()).or_default() += 1;
        // Two texts that contradict each other never stand in force together.
        if in_force.contains(s.target_proposal_id.as_str()) {
            blocked.insert(s.proposal_id.clone());
        }
        if in_force.contains(s.proposal_id.as_str()) {
            blocked.insert(s.target_proposal_id.clone());
        }
    }
    let (electorate, electorate_source) = electorate(state, &group).await?;
    Ok(DocState { doc, group, units, proposals, tallies, blocked, signal_counts, electorate, electorate_source })
}

impl DocState {
    pub fn tally(&self, id: &str) -> Tally {
        self.tallies.get(id).copied().unwrap_or_default()
    }

    pub fn unit_states(&self) -> Vec<UnitState> {
        let by_id: HashMap<&str, &ProposalRow> = self.proposals.iter().map(|p| (p.id.as_str(), p)).collect();
        self.units
            .iter()
            .map(|u| UnitState {
                id: u.id.clone(),
                position: u.position,
                inertia: inertia_of(u),
                in_force: u.in_force_id.as_deref().and_then(|id| by_id.get(id)).map(|p| VersionText {
                    id: p.id.clone(),
                    title: p.title.clone(),
                    body: p.body.clone(),
                    tally: self.tally(&p.id),
                }),
            })
            .collect()
    }

    /// Open proposals only — the in-force versions compete as incumbents.
    pub fn proposal_states(&self) -> Vec<ProposalState> {
        self.proposals
            .iter()
            .filter(|p| p.status == "open")
            .map(|p| ProposalState {
                id: p.id.clone(),
                unit_id: p.unit_id.clone(),
                kind: p.kind(),
                title: p.title.clone(),
                body: p.body.clone(),
                tally: self.tally(&p.id),
                submitted_at: p.submitted_at.clone().unwrap_or_else(|| p.created_at.clone()),
                blocked: self.blocked.contains(&p.id),
            })
            .collect()
    }

    pub fn evaluation(&self, unit: &UnitRow, p: &ProposalRow) -> Option<Evaluation> {
        let us = UnitState { id: unit.id.clone(), position: unit.position, inertia: inertia_of(unit), in_force: None };
        evaluate(self.tally(&p.id), self.electorate, &compose::params_for(&us, p.kind(), self.doc.vote_floor)).ok()
    }
}

// ---------------------------------------------------------------------------
// Document view
// ---------------------------------------------------------------------------

#[derive(sqlx::FromRow)]
struct TranslationRow {
    proposal_id: String,
    lang: String,
    title: String,
    body: String,
    source_hash: String,
    origin: String,
}

pub async fn translations_for(
    state: &AppState,
    ids: &[&ProposalRow],
) -> AppResult<HashMap<String, BTreeMap<String, serde_json::Value>>> {
    let mut out: HashMap<String, BTreeMap<String, serde_json::Value>> = HashMap::new();
    if ids.is_empty() {
        return Ok(out);
    }
    let marks = vec!["?"; ids.len()].join(",");
    let sql = format!(
        "SELECT proposal_id, lang, title, body, source_hash, origin FROM translations WHERE proposal_id IN ({marks})"
    );
    let mut q = sqlx::query_as::<_, TranslationRow>(&sql);
    for p in ids {
        q = q.bind(&p.id);
    }
    let rows = q.fetch_all(&state.db).await?;
    let current: HashMap<&str, String> =
        ids.iter().map(|p| (p.id.as_str(), util::source_hash(&p.title, &p.body))).collect();
    for r in rows {
        let stale = current.get(r.proposal_id.as_str()).is_none_or(|h| *h != r.source_hash);
        out.entry(r.proposal_id)
            .or_default()
            .insert(r.lang, json!({ "title": r.title, "body": r.body, "stale": stale, "origin": r.origin }));
    }
    Ok(out)
}

#[derive(sqlx::FromRow)]
struct MyVote {
    proposal_id: String,
    choice: String,
    revision: i64,
}

fn proposal_json(
    st: &DocState,
    unit: &UnitRow,
    p: &ProposalRow,
    mine: Option<&MyVote>,
    translations: Option<&BTreeMap<String, serde_json::Value>>,
    me: &str,
) -> serde_json::Value {
    let eval = st.evaluation(unit, p);
    let (kind, target) = match p.kind() {
        ProposalKind::Text => ("text", None),
        ProposalKind::Remove => ("remove", None),
        ProposalKind::Inertia(t) => ("inertia", Some(t.as_str())),
    };
    let voted_at = match p.kind() {
        ProposalKind::Inertia(_) => inertia_of(unit).raised(),
        _ => inertia_of(unit),
    };
    json!({
        "id": p.id, "unitId": p.unit_id, "kind": kind, "inertiaTarget": target,
        "title": p.title, "body": p.body, "status": p.status, "origin": p.origin, "label": p.label,
        "author": p.author_id.as_ref().map(|id| json!({ "id": id, "name": p.author_name })),
        "mine": p.author_id.as_deref() == Some(me),
        "revision": p.revision, "createdAt": p.created_at, "updatedAt": p.updated_at,
        "submittedAt": p.submitted_at, "enteredAt": p.entered_at, "confirmedAt": p.confirmed_at,
        "seedMinimal": p.status == "in_force" && p.entered_at.is_none() && p.confirmed_at.is_none() && p.origin == "seed",
        "tally": st.tally(&p.id),
        "evaluation": eval,
        "votedAtInertia": voted_at.as_str(),
        "blocked": st.blocked.contains(&p.id),
        "signals": st.signal_counts.get(&p.id).copied().unwrap_or(0),
        "myVote": mine.map(|v| v.choice.as_str()),
        "myVoteStale": mine.is_some_and(|v| v.revision != p.revision),
        "translations": translations.cloned().unwrap_or_default(),
    })
}

#[derive(Deserialize)]
pub struct DocQuery {}

pub async fn document(
    State(state): State<AppState>,
    User(user): User,
    Path(id): Path<String>,
) -> AppResult<Json<serde_json::Value>> {
    let st = load_state(&state, &id).await?;
    require_open(&state, &user, &st.group).await?;
    let visible: Vec<&ProposalRow> =
        st.proposals.iter().filter(|p| p.status != "draft" || p.author_id.as_deref() == Some(&user.id)).collect();
    let translations = translations_for(&state, &visible).await?;
    let mine: HashMap<String, MyVote> = sqlx::query_as::<_, MyVote>(
        "SELECT v.proposal_id, v.choice, v.revision FROM votes v JOIN proposals p ON p.id = v.proposal_id
         JOIN units u ON u.id = p.unit_id WHERE u.doc_id = ? AND v.identity_id = ?",
    )
    .bind(&id)
    .bind(&user.id)
    .fetch_all(&state.db)
    .await?
    .into_iter()
    .map(|v| (v.proposal_id.clone(), v))
    .collect();

    let units: Vec<_> = st
        .units
        .iter()
        .map(|u| {
            let of_unit: Vec<_> = visible
                .iter()
                .filter(|p| p.unit_id == u.id)
                .map(|p| proposal_json(&st, u, p, mine.get(&p.id), translations.get(&p.id), &user.id))
                .collect();
            let in_force = u
                .in_force_id
                .as_ref()
                .and_then(|fid| of_unit.iter().find(|p| p["id"].as_str() == Some(fid.as_str())).cloned());
            let proposals: Vec<_> = of_unit.into_iter().filter(|p| p["status"] != "in_force").collect();
            json!({
                "id": u.id, "code": u.code, "section": u.section, "position": u.position, "inertia": u.inertia,
                "inForce": in_force, "proposals": proposals,
            })
        })
        .collect();

    let publication = publication_status(&state, &id).await?;
    let can_vote = may_vote(&state, &user, &st.group).await?;
    Ok(Json(json!({
        "canVote": can_vote,
        "doc": {
            "id": st.doc.id, "slug": st.doc.slug, "groupSlug": st.group.slug, "groupName": st.group.name,
            "title": util::parse_lang(&st.doc.title), "summary": util::parse_lang(&st.doc.summary),
            "sourceLang": st.doc.source_lang, "voteFloor": st.doc.vote_floor,
            "electorate": st.electorate, "electorateSource": st.electorate_source,
            "formula": { "base": ld_engine::FormulaParams::DEFAULT_BASE },
            "publication": publication,
        },
        "units": units,
        "inertia": InertiaPreset::ALL.iter().map(|p| json!({
            "key": p.as_str(), "majorityPct": p.majority_pct(), "gradient": p.gradient(),
        })).collect::<Vec<_>>(),
    })))
}

pub async fn publication_status(state: &AppState, doc_id: &str) -> AppResult<serde_json::Value> {
    #[derive(sqlx::FromRow)]
    struct Row {
        created_at: String,
        done_at: Option<String>,
        commit_sha: Option<String>,
        last_error: Option<String>,
        attempts: i64,
    }
    let last = sqlx::query_as::<_, Row>(
        "SELECT created_at, done_at, commit_sha, last_error, attempts FROM outbox WHERE doc_id = ? ORDER BY id DESC LIMIT 1",
    )
    .bind(doc_id)
    .fetch_optional(&state.db)
    .await?;
    Ok(match last {
        None => json!({ "state": "none", "configured": state.cfg.publish.is_some() }),
        Some(r) => json!({
            "state": if r.done_at.is_some() { "done" } else { "pending" },
            "configured": state.cfg.publish.is_some(),
            "since": r.created_at, "doneAt": r.done_at, "commit": r.commit_sha,
            "attempts": r.attempts, "error": r.last_error.map(|_| "retrying"),
        }),
    })
}

#[derive(Deserialize)]
pub struct PreviewQuery {
    mode: Option<String>,
}

pub async fn preview(
    State(state): State<AppState>,
    User(user): User,
    Path(id): Path<String>,
    Query(q): Query<PreviewQuery>,
) -> AppResult<Json<serde_json::Value>> {
    let st = load_state(&state, &id).await?;
    require_open(&state, &user, &st.group).await?;
    let mode = match q.mode.as_deref() {
        Some("all") => PreviewMode::All,
        Some("wellrated") => PreviewMode::WellRated,
        _ => PreviewMode::InForce,
    };
    let units = compose::preview(&st.unit_states(), &st.proposal_states(), st.electorate, st.doc.vote_floor, mode)
        .map_err(|_| AppError::Invalid("electorate"))?;
    // Translations of the versions shown.
    let shown: HashSet<String> = units
        .iter()
        .map(|u| {
            u.proposal_id.clone().unwrap_or_else(|| {
                st.units.iter().find(|x| x.id == u.unit_id).and_then(|x| x.in_force_id.clone()).unwrap_or_default()
            })
        })
        .collect();
    let rows: Vec<&ProposalRow> = st.proposals.iter().filter(|p| shown.contains(&p.id)).collect();
    let tr = translations_for(&state, &rows).await?;
    let out: Vec<_> = units
        .into_iter()
        .map(|u| {
            let vid = u
                .proposal_id
                .clone()
                .or_else(|| st.units.iter().find(|x| x.id == u.unit_id).and_then(|x| x.in_force_id.clone()));
            let translations = vid.as_ref().and_then(|v| tr.get(v)).cloned().unwrap_or_default();
            json!({
                "unitId": u.unit_id, "title": u.title, "body": u.body, "mark": u.mark,
                "proposalId": u.proposal_id, "versionId": vid, "translations": translations,
            })
        })
        .collect();
    Ok(Json(json!({ "mode": q.mode.unwrap_or_else(|| "inforce".into()), "units": out })))
}

/// Unused for now; keeps the language list close to the documents.
pub fn source_langs() -> LangMap {
    util::LANGS.iter().map(|l| ((*l).to_owned(), String::new())).collect()
}