flatland-client-lib 0.2.13

//! Gfx sprite bundle sync for installed clients (Firebase Storage / GCS).

use std::collections::BTreeMap;
use std::io::Read;
use std::path::{Path, PathBuf};

use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};

pub const DEFAULT_FIREBASE_BUCKET: &str = "flatland-8911e.appspot.com";
pub const ASSETS_INDEX_OBJECT: &str = "flatland3/client-assets/latest.json";

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct AssetFileEntry {
    pub sha256: String,
    pub size: u64,
}

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct AssetBundleIndex {
    /// Stable revision from `assets/.content-publish.json` (not process-local `content_rev`).
    pub publish_rev: u64,
    pub published_at: String,
    pub files: BTreeMap<String, AssetFileEntry>,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct LocalAssetState {
    pub publish_rev: u64,
    pub sprites_dir: PathBuf,
}

pub fn assets_root_dir() -> anyhow::Result<PathBuf> {
    let base = dirs::home_dir().ok_or_else(|| anyhow::anyhow!("home directory not found"))?;
    Ok(base.join(".flatland3").join("assets"))
}

pub fn local_state_path() -> anyhow::Result<PathBuf> {
    Ok(assets_root_dir()?.join("state.json"))
}

pub fn read_local_state() -> Option<LocalAssetState> {
    let path = local_state_path().ok()?;
    let bytes = std::fs::read(path).ok()?;
    serde_json::from_slice(&bytes).ok()
}

pub fn write_local_state(state: &LocalAssetState) -> anyhow::Result<()> {
    let path = local_state_path()?;
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    std::fs::write(path, serde_json::to_vec_pretty(state)?)?;
    Ok(())
}

pub fn sprites_dir_for_rev(publish_rev: u64) -> anyhow::Result<PathBuf> {
    Ok(assets_root_dir()?.join(format!("rev-{publish_rev}")))
}

pub fn current_symlink_path() -> anyhow::Result<PathBuf> {
    Ok(assets_root_dir()?.join("current"))
}

pub fn activate_rev_dir(rev_dir: &Path) -> anyhow::Result<()> {
    let link = current_symlink_path()?;
    if link.exists() {
        std::fs::remove_file(&link).or_else(|_| std::fs::remove_dir_all(&link))?;
    }
    #[cfg(unix)]
    {
        std::os::unix::fs::symlink(rev_dir, &link)?;
    }
    #[cfg(not(unix))]
    {
        std::fs::write(link.with_extension("path"), rev_dir)?;
        std::fs::copy(
            rev_dir.join("manifest.yaml"),
            link.join("manifest.yaml"),
        )
        .ok();
    }
    Ok(())
}

pub fn find_repo_sprites_dir() -> Option<PathBuf> {
    let mut dir = std::env::current_dir().ok()?;
    for _ in 0..8 {
        let candidate = dir.join("assets/gfx/sprites");
        if candidate.join("manifest.yaml").is_file() {
            return Some(candidate);
        }
        if !dir.pop() {
            break;
        }
    }
    None
}

/// True when the checkout sprites should win over a synced `~/.flatland3` cache.
pub(crate) fn repo_sprites_outrank_cache(repo_rev: Option<u64>, local_rev: Option<u64>) -> bool {
    match (repo_rev, local_rev) {
        (Some(rr), Some(lr)) => rr >= lr,
        (Some(_), None) => true,
        _ => false,
    }
}

/// Prefer the repo checkout when it is at least as new as the synced cache.
///
/// Local play often has a stale `~/.flatland3/assets/rev-N` from an older sync.
/// `needs_asset_sync` already treats a matching repo as up to date, but loading
/// still went through the stale cache — so new sheets (e.g. lodging) fell back
/// to `other.default` after publish.
pub fn resolve_sprites_dir() -> Option<PathBuf> {
    if let Ok(p) = std::env::var("FLATLAND_SPRITES_DIR") {
        let path = PathBuf::from(p);
        if path.join("manifest.yaml").is_file() {
            return Some(path);
        }
    }

    let repo = find_repo_sprites_dir();
    let repo_rev = read_repo_publish_rev();
    let local = read_local_state().filter(|s| s.sprites_dir.join("manifest.yaml").is_file());
    let local_rev = local.as_ref().map(|s| s.publish_rev);

    if repo_sprites_outrank_cache(repo_rev, local_rev) {
        if let Some(repo_dir) = repo {
            return Some(repo_dir);
        }
    }
    if let Some(local) = local {
        return Some(local.sprites_dir);
    }
    if let Some(repo_dir) = repo {
        return Some(repo_dir);
    }

    let current = current_symlink_path().ok()?;
    if current.join("manifest.yaml").is_file() {
        return Some(current);
    }
    None
}

pub fn assets_index_url() -> String {
    std::env::var("FLATLAND_ASSETS_INDEX_URL").unwrap_or_else(|_| {
        firebase_download_url(DEFAULT_FIREBASE_BUCKET, ASSETS_INDEX_OBJECT)
    })
}

pub fn firebase_download_url(bucket: &str, object_path: &str) -> String {
    let encoded = urlencoding_encode(object_path);
    format!(
        "https://firebasestorage.googleapis.com/v0/b/{bucket}/o/{encoded}?alt=media"
    )
}

pub fn assets_storage_prefix() -> String {
    std::env::var("FLATLAND_ASSETS_PREFIX")
        .unwrap_or_else(|_| "flatland3/client-assets".to_string())
}

pub fn firebase_object_path_for_prefix(prefix: &str, publish_rev: u64, relative: &str) -> String {
    format!("{prefix}/rev-{publish_rev}/{relative}")
}

pub fn firebase_object_path(publish_rev: u64, relative: &str) -> String {
    firebase_object_path_for_prefix(&assets_storage_prefix(), publish_rev, relative)
}

fn urlencoding_encode(path: &str) -> String {
    path.bytes()
        .map(|b| match b {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
                (b as char).to_string()
            }
            _ => format!("%{b:02X}"),
        })
        .collect()
}

pub fn sha256_file(path: &Path) -> anyhow::Result<String> {
    let mut file = std::fs::File::open(path)?;
    let mut hasher = Sha256::new();
    let mut buf = [0u8; 8192];
    loop {
        let n = file.read(&mut buf)?;
        if n == 0 {
            break;
        }
        hasher.update(&buf[..n]);
    }
    Ok(hex::encode(hasher.finalize()))
}

/// Walk `assets/gfx/sprites` and build a publish manifest (relative paths → hash).
pub fn build_bundle_index(sprites_dir: &Path, publish_rev: u64, published_at: &str) -> anyhow::Result<AssetBundleIndex> {
    let mut files = BTreeMap::new();
    walk_sprites_dir(sprites_dir, sprites_dir, &mut files)?;
    Ok(AssetBundleIndex {
        publish_rev,
        published_at: published_at.to_string(),
        files,
    })
}

fn walk_sprites_dir(
    root: &Path,
    dir: &Path,
    files: &mut BTreeMap<String, AssetFileEntry>,
) -> anyhow::Result<()> {
    for entry in std::fs::read_dir(dir)? {
        let entry = entry?;
        let path = entry.path();
        if path.is_dir() {
            let name = entry.file_name();
            if name == "previews" {
                continue;
            }
            walk_sprites_dir(root, &path, files)?;
            continue;
        }
        let rel = path
            .strip_prefix(root)?
            .to_string_lossy()
            .replace('\\', "/");
        if rel.starts_with('.') || rel.contains("/.") {
            continue;
        }
        if rel.ends_with(".html") {
            continue;
        }
        let meta = std::fs::metadata(&path)?;
        files.insert(
            rel,
            AssetFileEntry {
                sha256: sha256_file(&path)?,
                size: meta.len(),
            },
        );
    }
    Ok(())
}

pub struct AssetSyncOptions {
    pub index_url: String,
    pub storage_prefix: String,
    pub target_rev: Option<u64>,
    pub quiet: bool,
}

/// Outcome of [`sync_assets`] for logging / HUD toasts.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AssetSyncKind {
    /// Downloaded or verified files against remote `latest.json`.
    Remote,
    /// Remote index missing; reused `~/.flatland3` cache.
    LocalCacheNoRemote,
    /// Remote index missing; using repo `assets/gfx/sprites` (dev checkout).
    RepoDevNoRemote,
}

#[derive(Debug, Clone)]
pub struct AssetSyncResult {
    pub state: LocalAssetState,
    pub kind: AssetSyncKind,
}

impl Default for AssetSyncOptions {
    fn default() -> Self {
        Self {
            index_url: assets_index_url(),
            storage_prefix: assets_storage_prefix(),
            target_rev: None,
            quiet: false,
        }
    }
}

pub async fn sync_assets(opts: AssetSyncOptions) -> anyhow::Result<AssetSyncResult> {
    // Local checkout: prefer repo sprites and skip remote download so gfx play does not
    // freeze on Firebase after login (no render loop until sync finishes).
    if std::env::var_os("FLATLAND_FORCE_ASSET_SYNC").is_none() {
        if let Some(repo_dir) = find_repo_sprites_dir() {
            if let Some(publish_rev) = read_repo_publish_rev() {
                if opts.target_rev.map_or(true, |t| publish_rev >= t) {
                    if !opts.quiet {
                        println!(
                            "Using repo sprites at {} (rev {publish_rev}); set FLATLAND_FORCE_ASSET_SYNC=1 to pull remote.",
                            repo_dir.display()
                        );
                    }
                    return Ok(AssetSyncResult {
                        state: LocalAssetState {
                            publish_rev,
                            sprites_dir: repo_dir,
                        },
                        kind: AssetSyncKind::RepoDevNoRemote,
                    });
                }
            }
        }
    }

    let client = reqwest::Client::builder()
        .user_agent(format!("flatland-client-lib/{}", env!("CARGO_PKG_VERSION")))
        .connect_timeout(std::time::Duration::from_secs(5))
        .timeout(std::time::Duration::from_secs(30))
        .build()?;
    let response = client.get(&opts.index_url).send().await?;
    if response.status() == reqwest::StatusCode::NOT_FOUND {
        return sync_without_remote_index(opts);
    }
    let index: AssetBundleIndex = response.error_for_status()?.json().await?;
    sync_from_index(&client, opts, index).await
}

fn sync_without_remote_index(opts: AssetSyncOptions) -> anyhow::Result<AssetSyncResult> {
    if let Some(local) = read_local_state() {
        if local.sprites_dir.join("manifest.yaml").is_file() {
            if !opts.quiet {
                println!(
                    "Remote latest.json not found; using cached publish rev {}.",
                    local.publish_rev
                );
            }
            return Ok(AssetSyncResult {
                state: local,
                kind: AssetSyncKind::LocalCacheNoRemote,
            });
        }
    }
    if let Some(repo) = find_repo_sprites_dir() {
        let publish_rev = read_repo_publish_rev().unwrap_or(0);
        if !opts.quiet {
            println!(
                "Remote latest.json not found; using repo sprites at {} (rev {publish_rev}).",
                repo.display()
            );
        }
        return Ok(AssetSyncResult {
            state: LocalAssetState {
                publish_rev,
                sprites_dir: repo,
            },
            kind: AssetSyncKind::RepoDevNoRemote,
        });
    }
    anyhow::bail!(
        "Gfx asset bundle not published yet (HTTP 404 on latest.json). \
         Server admin: flatland-admin content publish"
    );
}

async fn sync_from_index(
    client: &reqwest::Client,
    opts: AssetSyncOptions,
    index: AssetBundleIndex,
) -> anyhow::Result<AssetSyncResult> {
    let publish_rev = opts.target_rev.unwrap_or(index.publish_rev);
    if publish_rev != index.publish_rev {
        anyhow::bail!(
            "requested publish rev {publish_rev} but remote latest is {}",
            index.publish_rev
        );
    }

    if let Some(local) = read_local_state() {
        if local.publish_rev == publish_rev && local.sprites_dir.join("manifest.yaml").is_file() {
            if verify_rev_dir(&local.sprites_dir, &index)? {
                if !opts.quiet {
                    println!("Assets up to date (publish rev {publish_rev}).");
                }
                return Ok(AssetSyncResult {
                    state: local,
                    kind: AssetSyncKind::Remote,
                });
            }
        }
    }

    let rev_dir = sprites_dir_for_rev(publish_rev)?;
    std::fs::create_dir_all(&rev_dir)?;

    let total = index.files.len();
    let mut done = 0usize;
    for (rel, entry) in &index.files {
        let dest = rev_dir.join(rel);
        if dest.is_file() {
            if sha256_file(&dest)? == entry.sha256 {
                done += 1;
                continue;
            }
        }
        if let Some(parent) = dest.parent() {
            std::fs::create_dir_all(parent)?;
        }
        let url = firebase_download_url(
            DEFAULT_FIREBASE_BUCKET,
            &firebase_object_path_for_prefix(&opts.storage_prefix, publish_rev, rel),
        );
        let bytes = client.get(&url).send().await?.error_for_status()?.bytes().await?;
        if sha256_bytes(&bytes) != entry.sha256 {
            anyhow::bail!("hash mismatch for {rel} after download");
        }
        std::fs::write(&dest, &bytes)?;
        done += 1;
        if !opts.quiet {
            println!("  [{done}/{total}] {rel}");
        }
    }

    activate_rev_dir(&rev_dir)?;
    let state = LocalAssetState {
        publish_rev,
        sprites_dir: rev_dir,
    };
    write_local_state(&state)?;
    if !opts.quiet {
        println!(
            "Synced publish rev {publish_rev} → {}",
            state.sprites_dir.display()
        );
    }
    Ok(AssetSyncResult {
        state,
        kind: AssetSyncKind::Remote,
    })
}

pub fn needs_asset_sync(server_publish_rev: u64) -> bool {
    if server_publish_rev == 0 {
        return false;
    }
    if let Some(local) = read_local_state() {
        if local.publish_rev >= server_publish_rev
            && local.sprites_dir.join("manifest.yaml").is_file()
        {
            return false;
        }
    }
    if let Some(repo_rev) = read_repo_publish_rev() {
        if repo_rev >= server_publish_rev && find_repo_sprites_dir().is_some() {
            return false;
        }
    }
    resolve_sprites_dir().is_none()
}

/// Publish rev from `assets/.content-publish.json` when running from a dev checkout.
pub fn read_repo_publish_rev() -> Option<u64> {
    let sprites = find_repo_sprites_dir()?;
    let mut dir = sprites.as_path();
    for _ in 0..8 {
        let marker = dir.join(".content-publish.json");
        if marker.is_file() {
            #[derive(Deserialize)]
            struct Marker {
                rev: u64,
            }
            let text = std::fs::read_to_string(marker).ok()?;
            let m: Marker = serde_json::from_str(&text).ok()?;
            return Some(m.rev);
        }
        dir = dir.parent()?;
    }
    None
}

fn verify_rev_dir(dir: &Path, index: &AssetBundleIndex) -> anyhow::Result<bool> {
    for (rel, entry) in &index.files {
        let path = dir.join(rel);
        if !path.is_file() {
            return Ok(false);
        }
        if sha256_file(&path)? != entry.sha256 {
            return Ok(false);
        }
    }
    Ok(true)
}

fn sha256_bytes(bytes: &[u8]) -> String {
    let mut hasher = Sha256::new();
    hasher.update(bytes);
    hex::encode(hasher.finalize())
}

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

    #[test]
    fn firebase_url_encodes_slashes() {
        let url = firebase_download_url("bucket", "flatland3/client-assets/latest.json");
        assert!(url.contains("%2F"));
        assert!(url.contains("alt=media"));
    }

    #[test]
    fn build_index_hashes_files() {
        let dir = std::env::temp_dir().join(format!("flatland-assets-test-{}", std::process::id()));
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(dir.join("cells")).expect("dir");
        fs::write(dir.join("manifest.yaml"), "version: 1\n").expect("write");
        fs::write(dir.join("cells/a.png"), b"png").expect("write");
        let index = build_bundle_index(&dir, 3, "2026-01-01T00:00:00Z").expect("index");
        assert_eq!(index.publish_rev, 3);
        assert_eq!(index.files.len(), 2);
        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn needs_sync_false_when_repo_matches_server_rev() {
        if read_repo_publish_rev().is_some() && find_repo_sprites_dir().is_some() {
            let rev = read_repo_publish_rev().unwrap();
            assert!(!needs_asset_sync(rev));
        }
    }

    #[test]
    fn repo_outranks_stale_synced_cache() {
        assert!(repo_sprites_outrank_cache(Some(85), Some(75)));
        assert!(repo_sprites_outrank_cache(Some(75), Some(75)));
        assert!(!repo_sprites_outrank_cache(Some(70), Some(75)));
        assert!(repo_sprites_outrank_cache(Some(85), None));
        assert!(!repo_sprites_outrank_cache(None, Some(75)));
    }
}