//! Site administration (hub spec §6.3 `/admin/*`): accounts, registration
//! mode and invitations, the audit log.

use super::settings::csrf;
use super::{filters, Error, Page, Shell};
use crate::auth::{self, Viewer};
use crate::db::accounts;
use crate::Shared;
use askama::Template;
use axum::extract::{Form, State};
use serde::Deserialize;

#[derive(Template)]
#[template(path = "admin.html")]
pub struct AdminPage {
    shell: Shell,
    accounts: Vec<accounts::Account>,
    orgs: Vec<accounts::Organisation>,
    mode: String,
    invitations: Vec<(String, Option<i64>, i64)>,
    audit: Vec<accounts::AuditRow>,
    repos: usize,
    notice: Option<String>,
}

fn require_admin(viewer: &Viewer, shell: &Shell) -> Result<accounts::Account, Error> {
    match viewer.account() {
        Some(a) if a.is_admin => Ok(a.clone()),
        _ => Err(Error::not_found(shell.clone())),
    }
}

async fn admin_page(app: &Shared, shell: Shell, notice: Option<String>) -> Result<Page<AdminPage>, Error> {
    let e = |e| Error::from_db(shell.clone(), e);
    let accounts_list = accounts::accounts(&app.db).await.map_err(e)?;
    let orgs = accounts::orgs(&app.db).await.map_err(e)?;
    let mode = super::session::registration_mode(app).await;
    let invitations = accounts::invitations(&app.db).await.map_err(e)?;
    let audit = accounts::audit_rows(&app.db, 100).await.map_err(e)?;
    let repos = crate::db::repos::list(&app.db).await.map_err(e)?.len();
    Ok(Page(AdminPage { shell, accounts: accounts_list, orgs, mode, invitations, audit, repos, notice }))
}

pub async fn index(State(app): State<Shared>, viewer: Viewer) -> Result<Page<AdminPage>, Error> {
    let shell = Shell::new(&app, "/admin", &viewer);
    require_admin(&viewer, &shell)?;
    admin_page(&app, shell, None).await
}

#[derive(Deserialize)]
pub struct ModeForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    mode: String,
}

pub async fn set_mode(State(app): State<Shared>, viewer: Viewer, Form(f): Form<ModeForm>) -> Result<Page<AdminPage>, Error> {
    let shell = Shell::new(&app, "/admin", &viewer);
    let me = require_admin(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    if !matches!(f.mode.as_str(), "open" | "invite" | "closed") {
        return Err(Error::bad(shell, "mode is open, invite or closed"));
    }
    accounts::set_setting(&app.db, "registration_mode", &f.mode).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me), "admin.registration", &f.mode, "").await.ok();
    admin_page(&app, shell, Some(format!("Registration is {}.", f.mode))).await
}

pub async fn invite(State(app): State<Shared>, viewer: Viewer, Form(f): Form<super::session::CsrfForm>) -> Result<Page<AdminPage>, Error> {
    let shell = Shell::new(&app, "/admin", &viewer);
    let me = require_admin(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    let code = auth::random_hex(12);
    accounts::create_invitation(&app.db, &code, Some(me.id)).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me), "admin.invite", &code, "").await.ok();
    admin_page(&app, shell, Some(format!("Invitation created: {}/register?invite={code}", app.config.base_url()))).await
}

#[derive(Deserialize)]
pub struct AccountForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    username: String,
    action: String,
    /// For delete: the username typed again.
    #[serde(default)]
    confirm: String,
}

pub async fn account(State(app): State<Shared>, viewer: Viewer, Form(f): Form<AccountForm>) -> Result<Page<AdminPage>, Error> {
    let shell = Shell::new(&app, "/admin", &viewer);
    let me = require_admin(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let Some(target) = accounts::account_by_name(&app.db, f.username.trim()).await.map_err(|e| Error::from_db(shell.clone(), e))? else {
        return admin_page(&app, shell, Some("No such account.".into())).await;
    };
    if target.id == me.id && matches!(f.action.as_str(), "ban" | "demote" | "disable" | "delete") {
        return admin_page(&app, shell, Some("Not on yourself.".into())).await;
    }
    let e = |e| Error::from_db(shell.clone(), e);
    // The hub must keep an admin who can sign in (oxygenhub#81).
    if target.is_admin && matches!(f.action.as_str(), "disable" | "delete") {
        let others =
            accounts::accounts(&app.db).await.map_err(e)?.into_iter().filter(|a| a.is_admin && !a.blocked() && a.id != target.id).count();
        if others == 0 {
            return admin_page(&app, shell, Some(format!("{} is the last admin who can sign in.", target.username))).await;
        }
    }
    if f.action == "delete" {
        if f.confirm.trim() != target.username {
            return admin_page(&app, shell, Some(format!("Not deleted: type {} to confirm.", target.username))).await;
        }
        let repos = crate::db::repos::list_by_owner(&app.db, &target.username).await.map_err(e)?;
        let orgs = accounts::orgs_owned_only_by(&app.db, target.id).await.map_err(e)?;
        if !repos.is_empty() || !orgs.is_empty() {
            let mut held: Vec<String> = repos.iter().map(|r| r.slug()).collect();
            held.extend(orgs.iter().map(|o| format!("organisation {o} (sole owner)")));
            return admin_page(
                &app,
                shell,
                Some(format!("Not deleted: {} still owns {}. Transfer or delete them first.", target.username, held.join(", "))),
            )
            .await;
        }
        accounts::delete_account(&app.db, target.id, &target.username).await.map_err(e)?;
        accounts::audit(&app.db, Some(&me), "admin.account.delete", &target.username, "").await.ok();
        return admin_page(&app, shell, Some(format!("{} deleted; the name stays retired.", target.username))).await;
    }
    if f.action == "reset_link" {
        if target.blocked() {
            return admin_page(&app, shell, Some("A banned or disabled account cannot be reset.".into())).await;
        }
        let url = super::recovery::admin_reset_link(&app, &me, &target).await.map_err(e)?;
        return admin_page(
            &app,
            shell,
            Some(format!("Reset link for {} (works once, for 24 hours; shown only now): {url}", target.username)),
        )
        .await;
    }
    match f.action.as_str() {
        "ban" => accounts::set_banned(&app.db, target.id, true).await.map_err(e)?,
        "unban" => accounts::set_banned(&app.db, target.id, false).await.map_err(e)?,
        "disable" => accounts::set_disabled(&app.db, target.id, true).await.map_err(e)?,
        "enable" => accounts::set_disabled(&app.db, target.id, false).await.map_err(e)?,
        "promote" => accounts::set_admin(&app.db, target.id, true).await.map_err(e)?,
        "demote" => accounts::set_admin(&app.db, target.id, false).await.map_err(e)?,
        _ => return Err(Error::bad(shell, "unknown action")),
    }
    accounts::audit(&app.db, Some(&me), &format!("admin.account.{}", f.action), &target.username, "").await.ok();
    admin_page(&app, shell, Some(format!("{}: {}.", target.username, f.action))).await
}

// ------------------------------------------------------------------ storage

/// One repository's footprint on disk.
pub struct StorageRow {
    pub slug: String,
    pub bytes: u64,
    /// Objects not yet in a pack.
    pub loose: usize,
    pub packs: usize,
}

#[derive(Template)]
#[template(path = "admin_storage.html")]
pub struct StoragePage {
    shell: Shell,
    rows: Vec<StorageRow>,
    total: u64,
    notice: Option<String>,
    error: Option<String>,
}

/// Size, loose objects and packs under a repository directory.
fn footprint(dir: &std::path::Path) -> (u64, usize, usize) {
    let (mut bytes, mut loose, mut packs) = (0u64, 0usize, 0usize);
    let mut stack = vec![dir.to_path_buf()];
    while let Some(d) = stack.pop() {
        let Ok(rd) = std::fs::read_dir(&d) else { continue };
        for e in rd.flatten() {
            let Ok(ft) = e.file_type() else { continue };
            if ft.is_dir() {
                stack.push(e.path());
            } else if ft.is_file() {
                bytes += e.metadata().map(|m| m.len()).unwrap_or(0);
                let p = e.path();
                if p.components().any(|c| c.as_os_str() == "loose") {
                    loose += 1;
                } else if p.extension().is_some_and(|x| x == "pack") {
                    packs += 1;
                }
            }
        }
    }
    (bytes, loose, packs)
}

async fn storage_page(app: &Shared, shell: Shell, notice: Option<String>, error: Option<String>) -> Result<Page<StoragePage>, Error> {
    let repos = crate::db::repos::list(&app.db).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let dirs: Vec<(String, std::path::PathBuf)> =
        repos.iter().filter_map(|r| crate::repos::RepoName::new(&r.owner, &r.name).map(|n| (n.to_string(), app.repos.dir(&n)))).collect();
    let mut rows = tokio::task::spawn_blocking(move || {
        dirs.into_iter()
            .map(|(slug, dir)| {
                let (bytes, loose, packs) = footprint(&dir);
                StorageRow { slug, bytes, loose, packs }
            })
            .collect::<Vec<_>>()
    })
    .await
    .unwrap_or_default();
    rows.sort_by_key(|r| std::cmp::Reverse(r.bytes));
    let total = rows.iter().map(|r| r.bytes).sum();
    Ok(Page(StoragePage { shell, rows, total, notice, error }))
}

pub async fn storage(State(app): State<Shared>, viewer: Viewer) -> Result<Page<StoragePage>, Error> {
    let shell = Shell::new(&app, "/admin/storage", &viewer);
    require_admin(&viewer, &shell)?;
    storage_page(&app, shell, None, None).await
}

#[derive(Deserialize)]
pub struct MaintainForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    /// `owner/name`, or `*` for every repository.
    repo: String,
}

/// `POST /admin/storage`: `oxy gc` on one repository or all of them, under
/// each repository's write lock, with the grace period kept.
pub async fn maintain(State(app): State<Shared>, viewer: Viewer, Form(f): Form<MaintainForm>) -> Result<Page<StoragePage>, Error> {
    let shell = Shell::new(&app, "/admin/storage", &viewer);
    let me = require_admin(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let names: Vec<crate::repos::RepoName> = if f.repo == "*" {
        crate::db::repos::list(&app.db)
            .await
            .map_err(|e| Error::from_db(shell.clone(), e))?
            .iter()
            .filter_map(|r| crate::repos::RepoName::new(&r.owner, &r.name))
            .collect()
    } else {
        match crate::repos::RepoName::parse(&f.repo) {
            Some(n) if app.repos.exists(&n) => vec![n],
            _ => return storage_page(&app, shell, None, Some(format!("No repository {}.", f.repo))).await,
        }
    };
    let (mut packed, mut pruned, mut freed, mut failed) = (0usize, 0usize, 0u64, Vec::new());
    for name in &names {
        match app.repos.write(name, |r, _| r.gc(false).map_err(crate::repos::RepoError::Oxy)).await {
            Ok(rep) => {
                packed += rep.packed.objects;
                pruned += rep.pruned.objects;
                freed += rep.pruned.bytes + rep.packed.raw_bytes.saturating_sub(rep.packed.packed_bytes);
            }
            Err(e) => failed.push(format!("{name}: {e}")),
        }
    }
    let summary = format!(
        "Maintained {} repositor{}: {packed} loose objects packed, {pruned} unreachable objects pruned, about {} saved.",
        names.len(),
        if names.len() == 1 { "y" } else { "ies" },
        crate::render::bytes(freed)
    );
    accounts::audit(&app.db, Some(&me), "admin.gc", &f.repo, &summary).await.ok();
    let error = (!failed.is_empty()).then(|| failed.join("; "));
    storage_page(&app, shell, Some(summary), error).await
}