use std::fs::{File, create_dir_all};
use std::io::{self, Read, Write};
use std::path::Path;
use std::collections::BTreeMap;
use std::time::Duration;
use std::env;

use anyhow::{anyhow, Context, Result};
use serde::Deserialize;
use reqwest::blocking::Client;
use reqwest::redirect::Policy;
use sha2::{Digest, Sha256};

// --- Model downloader: list & download ggml models from Hugging Face ---

#[derive(Debug, Deserialize)]
struct HFLfsMeta {
    oid: Option<String>,
    size: Option<u64>,
    sha256: Option<String>,
}

#[derive(Debug, Deserialize)]
struct HFSibling {
    rfilename: String,
    size: Option<u64>,
    sha256: Option<String>,
    lfs: Option<HFLfsMeta>,
}

#[derive(Debug, Deserialize)]
struct HFRepoInfo {
    // When using ?expand=files the field is named 'siblings'
    siblings: Option<Vec<HFSibling>>,
}

#[derive(Debug, Deserialize)]
struct HFTreeItem {
    path: String,
    size: Option<u64>,
    sha256: Option<String>,
    lfs: Option<HFLfsMeta>,
}

#[derive(Clone, Debug, Deserialize)]
struct ModelEntry {
    // e.g. "tiny.en-q5_1"
    name: String,
    base: String,
    subtype: String,
    size: u64,
    sha256: Option<String>,
    repo: String, // e.g. "ggerganov/whisper.cpp"
}

fn split_model_name(model: &str) -> (String, String) {
    let mut idx = None;
    for (i, ch) in model.char_indices() {
        if ch == '.' || ch == '-' {
            idx = Some(i);
            break;
        }
    }
    if let Some(i) = idx {
        (model[..i].to_string(), model[i + 1..].to_string())
    } else {
        (model.to_string(), String::new())
    }
}

fn human_size(bytes: u64) -> String {
    const KB: f64 = 1024.0;
    const MB: f64 = KB * 1024.0;
    const GB: f64 = MB * 1024.0;
    let b = bytes as f64;
    if b >= GB { format!("{:.2} GiB", b / GB) }
    else if b >= MB { format!("{:.2} MiB", b / MB) }
    else if b >= KB { format!("{:.2} KiB", b / KB) }
    else { format!("{} B", bytes) }
}

fn to_hex_lower(bytes: &[u8]) -> String {
    let mut s = String::with_capacity(bytes.len() * 2);
    for b in bytes { s.push_str(&format!("{:02x}", b)); }
    s
}

fn expected_sha_from_sibling(s: &HFSibling) -> Option<String> {
    if let Some(h) = &s.sha256 { return Some(h.to_lowercase()); }
    if let Some(lfs) = &s.lfs {
        if let Some(h) = &lfs.sha256 { return Some(h.to_lowercase()); }
        if let Some(oid) = &lfs.oid {
            // e.g. "sha256:abcdef..."
            if let Some(rest) = oid.strip_prefix("sha256:") {
                return Some(rest.to_lowercase().to_string());
            }
        }
    }
    None
}

fn size_from_sibling(s: &HFSibling) -> Option<u64> {
    if let Some(sz) = s.size { return Some(sz); }
    if let Some(lfs) = &s.lfs { return lfs.size; }
    None
}

fn expected_sha_from_tree(s: &HFTreeItem) -> Option<String> {
    if let Some(h) = &s.sha256 { return Some(h.to_lowercase()); }
    if let Some(lfs) = &s.lfs {
        if let Some(h) = &lfs.sha256 { return Some(h.to_lowercase()); }
        if let Some(oid) = &lfs.oid {
            if let Some(rest) = oid.strip_prefix("sha256:") {
                return Some(rest.to_lowercase().to_string());
            }
        }
    }
    None
}

fn size_from_tree(s: &HFTreeItem) -> Option<u64> {
    if let Some(sz) = s.size { return Some(sz); }
    if let Some(lfs) = &s.lfs { return lfs.size; }
    None
}

fn fill_meta_via_head(repo: &str, name: &str) -> (Option<u64>, Option<String>) {
    let head_client = match Client::builder()
        .user_agent("PolyScribe/0.1 (+https://github.com/)")
        .redirect(Policy::none())
        .timeout(Duration::from_secs(30))
        .build() {
        Ok(c) => c,
        Err(_) => return (None, None),
    };
    let url = format!("https://huggingface.co/{}/resolve/main/ggml-{}.bin", repo, name);
    let resp = match head_client.head(url).send().and_then(|r| r.error_for_status()) {
        Ok(r) => r,
        Err(_) => return (None, None),
    };
    let headers = resp.headers();
    let size = headers
        .get("x-linked-size")
        .and_then(|v| v.to_str().ok())
        .and_then(|s| s.parse::<u64>().ok());
    let mut sha = headers
        .get("x-linked-etag")
        .and_then(|v| v.to_str().ok())
        .map(|s| s.trim().trim_matches('"').to_string());
    if let Some(h) = &mut sha {
        h.make_ascii_lowercase();
        if h.len() != 64 || !h.chars().all(|c| c.is_ascii_hexdigit()) {
            sha = None;
        }
    }
    // Fallback: try x-xet-hash header if x-linked-etag is missing/invalid
    if sha.is_none() {
        sha = headers
            .get("x-xet-hash")
            .and_then(|v| v.to_str().ok())
            .map(|s| s.trim().trim_matches('"').to_string());
        if let Some(h) = &mut sha {
            h.make_ascii_lowercase();
            if h.len() != 64 || !h.chars().all(|c| c.is_ascii_hexdigit()) {
                sha = None;
            }
        }
    }
    (size, sha)
}

fn hf_fetch_repo_models(client: &Client, repo: &'static str) -> Result<Vec<ModelEntry>> {
    eprintln!("Fetching online data: listing models from {}...", repo);
    // Prefer the tree endpoint for reliable size/hash metadata, then fall back to model metadata
    let tree_url = format!("https://huggingface.co/api/models/{}/tree/main?recursive=1", repo);
    let mut out: Vec<ModelEntry> = Vec::new();

    match client.get(tree_url).send().and_then(|r| r.error_for_status()) {
        Ok(resp) => {
            match resp.json::<Vec<HFTreeItem>>() {
                Ok(items) => {
                    for it in items {
                        let path = it.path.clone();
                        if !(path.starts_with("ggml-") && path.ends_with(".bin")) { continue; }
                        let model_name = path.trim_start_matches("ggml-").trim_end_matches(".bin").to_string();
                        let (base, subtype) = split_model_name(&model_name);
                        let size = size_from_tree(&it).unwrap_or(0);
                        let sha256 = expected_sha_from_tree(&it);
                        out.push(ModelEntry { name: model_name, base, subtype, size, sha256, repo: repo.to_string() });
                    }
                }
                Err(_) => { /* fall back below */ }
            }
        }
        Err(_) => { /* fall back below */ }
    }

    if out.is_empty() {
        let url = format!("https://huggingface.co/api/models/{}", repo);
        let resp = client
            .get(url)
            .send()
            .and_then(|r| r.error_for_status())
            .context("Failed to query Hugging Face API")?;

        let info: HFRepoInfo = resp.json().context("Failed to parse Hugging Face API response")?;

        if let Some(files) = info.siblings {
            for s in files {
                let rf = s.rfilename.clone();
                if !(rf.starts_with("ggml-") && rf.ends_with(".bin")) { continue; }
                let model_name = rf.trim_start_matches("ggml-").trim_end_matches(".bin").to_string();
                let (base, subtype) = split_model_name(&model_name);
                let size = size_from_sibling(&s).unwrap_or(0);
                let sha256 = expected_sha_from_sibling(&s);
                out.push(ModelEntry { name: model_name, base, subtype, size, sha256, repo: repo.to_string() });
            }
        }
    }

    // Fill missing metadata (size/hash) via HEAD request if necessary
    if out.iter().any(|m| m.size == 0 || m.sha256.is_none()) {
        eprintln!("Fetching online data: completing metadata checks for models in {}...", repo);
    }
    for m in out.iter_mut() {
        if m.size == 0 || m.sha256.is_none() {
            let (sz, sha) = fill_meta_via_head(&m.repo, &m.name);
            if m.size == 0 {
                if let Some(s) = sz { m.size = s; }
            }
            if m.sha256.is_none() {
                m.sha256 = sha;
            }
        }
    }

    // Sort by base then subtype then name for stable listing
    out.sort_by(|a, b| a.base.cmp(&b.base).then(a.subtype.cmp(&b.subtype)).then(a.name.cmp(&b.name)));
    Ok(out)
}

fn fetch_all_models(client: &Client) -> Result<Vec<ModelEntry>> {
    eprintln!("Fetching online data: aggregating available models from Hugging Face...");
    let mut v1 = hf_fetch_repo_models(client, "ggerganov/whisper.cpp")?; // main repo must succeed

    // Optional tinydiarize repo; ignore errors but log to stderr
    let mut v2: Vec<ModelEntry> = match hf_fetch_repo_models(client, "akashmjn/tinydiarize-whisper.cpp") {
        Ok(v) => v,
        Err(e) => {
            eprintln!("Warning: failed to fetch optional repo akashmjn/tinydiarize-whisper.cpp: {:#}", e);
            Vec::new()
        }
    };

    v1.append(&mut v2);

    // Deduplicate by name preferring ggerganov repo if duplicates
    let mut map: BTreeMap<String, ModelEntry> = BTreeMap::new();
    for m in v1 {
        map.entry(m.name.clone()).and_modify(|existing| {
            if existing.repo != "ggerganov/whisper.cpp" && m.repo == "ggerganov/whisper.cpp" {
                *existing = m.clone();
            }
        }).or_insert(m);
    }

    let mut list: Vec<ModelEntry> = map.into_values().collect();
    list.sort_by(|a, b| a.base.cmp(&b.base).then(a.subtype.cmp(&b.subtype)).then(a.name.cmp(&b.name)));
    Ok(list)
}


fn prompt_select_models(models: &[ModelEntry]) -> Result<Vec<ModelEntry>> {
    // Build a flat list but show group headers; indices count only models
    println!("Available ggml Whisper models:");
    let mut idx = 1usize;
    let mut current = "".to_string();
    // We'll record mapping from index -> position in models
    let mut index_map: Vec<usize> = Vec::with_capacity(models.len());
    for (pos, m) in models.iter().enumerate() {
        if m.base != current {
            current = m.base.clone();
            println!("\n{}:", current);
        }
        let short_hash = m
            .sha256
            .as_ref()
            .map(|h| h.chars().take(8).collect::<String>())
            .unwrap_or_else(|| "-".to_string());
        println!("  {}) {}  [{} | {} | {}]", idx, m.name, m.repo, human_size(m.size), short_hash);
        index_map.push(pos);
        idx += 1;
    }
    println!("\nEnter selection by indices (e.g., 1 3 5-7), or 'all', '*' for all, 'q' to cancel.");
    loop {
        eprint!("Selection: ");
        io::stderr().flush().ok();
        let mut line = String::new();
        io::stdin().read_line(&mut line).context("Failed to read selection")?;
        let s = line.trim().to_lowercase();
        if s == "q" || s == "quit" || s == "exit" { return Ok(Vec::new()); }
        let mut selected: Vec<usize> = Vec::new();
        if s == "all" || s == "*" {
            selected = (1..idx).collect();
        } else if !s.is_empty() {
            for part in s.split(|c| c == ',' || c == ' ' || c == ';') {
                let part = part.trim();
                if part.is_empty() { continue; }
                if let Some((a, b)) = part.split_once('-') {
                    if let (Ok(ia), Ok(ib)) = (a.parse::<usize>(), b.parse::<usize>()) {
                        if ia >= 1 && ib < idx && ia <= ib { selected.extend(ia..=ib); }
                    }
                } else if let Ok(i) = part.parse::<usize>() {
                    if i >= 1 && i < idx { selected.push(i); }
                }
            }
        }
        selected.sort_unstable();
        selected.dedup();
        if selected.is_empty() {
            eprintln!("No valid selection. Please try again or 'q' to cancel.");
            continue;
        }
        let chosen: Vec<ModelEntry> = selected.into_iter().map(|i| models[index_map[i - 1]].clone()).collect();
        return Ok(chosen);
    }
}

fn compute_file_sha256_hex(path: &Path) -> Result<String> {
    let file = File::open(path)
        .with_context(|| format!("Failed to open for hashing: {}", path.display()))?;
    let mut reader = std::io::BufReader::new(file);
    let mut hasher = Sha256::new();
    let mut buf = [0u8; 1024 * 128];
    loop {
        let n = reader.read(&mut buf).context("Read error during hashing")?;
        if n == 0 { break; }
        hasher.update(&buf[..n]);
    }
    Ok(to_hex_lower(&hasher.finalize()))
}

fn models_dir_path() -> std::path::PathBuf {
    if let Ok(p) = env::var("POLYSCRIBE_MODELS_DIR") {
        let pb = std::path::PathBuf::from(p);
        if !pb.as_os_str().is_empty() { return pb; }
    }
    if cfg!(debug_assertions) {
        std::path::PathBuf::from("models")
    } else {
        std::path::PathBuf::from("/usr/share/polyscribe/models")
    }
}

pub fn run_interactive_model_downloader() -> Result<()> {
    let models_dir_buf = models_dir_path();
    let models_dir = models_dir_buf.as_path();
    if !models_dir.exists() { create_dir_all(models_dir).context("Failed to create models directory")?; }
    let client = Client::builder()
        .user_agent("PolyScribe/0.1 (+https://github.com/)")
        .timeout(std::time::Duration::from_secs(600))
        .build()
        .context("Failed to build HTTP client")?;

    eprintln!("Fetching online data: contacting Hugging Face to retrieve available models (this may take a moment)...");
    let models = fetch_all_models(&client)?;
    if models.is_empty() {
        eprintln!("No models found on Hugging Face listing. Please try again later.");
        return Ok(());
    }
    let selected = prompt_select_models(&models)?;
    if selected.is_empty() {
        eprintln!("No selection. Aborting download.");
        return Ok(());
    }
    for m in selected {
        if let Err(e) = download_one_model(&client, models_dir, &m) { eprintln!("Error: {:#}", e); }
    }
    Ok(())
}

pub fn download_one_model(client: &Client, models_dir: &Path, entry: &ModelEntry) -> Result<()> {
    let final_path = models_dir.join(format!("ggml-{}.bin", entry.name));

    // If the model already exists, verify against online metadata
    if final_path.exists() {
        if let Some(expected) = &entry.sha256 {
            match compute_file_sha256_hex(&final_path) {
                Ok(local_hash) => {
                    if local_hash.eq_ignore_ascii_case(expected) {
                        eprintln!("Model {} is up-to-date (hash match).", final_path.display());
                        return Ok(());
                    } else {
                        eprintln!(
                            "Local model {} hash differs from online (local {}.., online {}..). Updating...",
                            final_path.display(),
                            &local_hash[..std::cmp::min(8, local_hash.len())],
                            &expected[..std::cmp::min(8, expected.len())]
                        );
                    }
                }
                Err(e) => {
                    eprintln!(
                        "Warning: failed to hash existing {}: {}. Will re-download to ensure correctness.",
                        final_path.display(), e
                    );
                }
            }
        } else if entry.size > 0 {
            match std::fs::metadata(&final_path) {
                Ok(md) => {
                    if md.len() == entry.size {
                        eprintln!(
                            "Model {} appears up-to-date by size ({}).",
                            final_path.display(), entry.size
                        );
                        return Ok(());
                    } else {
                        eprintln!(
                            "Local model {} size ({}) differs from online ({}). Updating...",
                            final_path.display(), md.len(), entry.size
                        );
                    }
                }
                Err(e) => {
                    eprintln!(
                        "Warning: failed to stat existing {}: {}. Will re-download to ensure correctness.",
                        final_path.display(), e
                    );
                }
            }
        } else {
            eprintln!(
                "Model {} exists but remote hash/size not available; will download to verify contents.",
                final_path.display()
            );
            // Fall through to download/copy for content comparison
        }
    }

    // Offline/local copy mode for tests: if set, copy from a given base directory instead of HTTP
    if let Ok(base_dir) = env::var("POLYSCRIBE_MODELS_BASE_COPY_DIR") {
        let src_path = std::path::Path::new(&base_dir).join(format!("ggml-{}.bin", entry.name));
        if src_path.exists() {
            eprintln!("Copying {} from {}...", entry.name, src_path.display());
            let tmp_path = models_dir.join(format!("ggml-{}.bin.part", entry.name));
            if tmp_path.exists() { let _ = std::fs::remove_file(&tmp_path); }
            std::fs::copy(&src_path, &tmp_path)
                .with_context(|| format!("Failed to copy from {} to {}", src_path.display(), tmp_path.display()))?;
            // Verify hash if available
            if let Some(expected) = &entry.sha256 {
                let got = compute_file_sha256_hex(&tmp_path)?;
                if !got.eq_ignore_ascii_case(expected) {
                    let _ = std::fs::remove_file(&tmp_path);
                    return Err(anyhow!(
                        "SHA-256 mismatch for {} (copied): expected {}, got {}",
                        entry.name, expected, got
                    ));
                }
            }
            // Replace existing file safely
            if final_path.exists() { let _ = std::fs::remove_file(&final_path); }
            std::fs::rename(&tmp_path, &final_path)
                .with_context(|| format!("Failed to move into place: {}", final_path.display()))?;
            eprintln!("Saved: {}", final_path.display());
            return Ok(());
        }
    }

    let url = format!("https://huggingface.co/{}/resolve/main/ggml-{}.bin", entry.repo, entry.name);
    eprintln!("Downloading {} ({} | {})...", entry.name, human_size(entry.size), url);
    let mut resp = client
        .get(url)
        .send()
        .and_then(|r| r.error_for_status())
        .context("Failed to download model")?;

    let tmp_path = models_dir.join(format!("ggml-{}.bin.part", entry.name));
    if tmp_path.exists() {
        let _ = std::fs::remove_file(&tmp_path);
    }
    let mut file = std::io::BufWriter::new(
        File::create(&tmp_path)
            .with_context(|| format!("Failed to create {}", tmp_path.display()))?
    );

    let mut hasher = Sha256::new();
    let mut buf = [0u8; 1024 * 128];
    loop {
        let n = resp.read(&mut buf).context("Network read error")?;
        if n == 0 { break; }
        hasher.update(&buf[..n]);
        file.write_all(&buf[..n]).context("Write error")?;
    }
    file.flush().ok();

    let got = to_hex_lower(&hasher.finalize());
    if let Some(expected) = &entry.sha256 {
        if got != expected.to_lowercase() {
            let _ = std::fs::remove_file(&tmp_path);
            return Err(anyhow!(
                "SHA-256 mismatch for {}: expected {}, got {}",
                entry.name, expected, got
            ));
        }
    } else {
        eprintln!("Warning: no SHA-256 available for {}. Skipping verification.", entry.name);
    }
    // Replace existing file safely
    if final_path.exists() {
        let _ = std::fs::remove_file(&final_path);
    }
    std::fs::rename(&tmp_path, &final_path)
        .with_context(|| format!("Failed to move into place: {}", final_path.display()))?;
    eprintln!("Saved: {}", final_path.display());
    Ok(())
}

pub fn update_local_models() -> Result<()> {
    let models_dir_buf = models_dir_path();
    let models_dir = models_dir_buf.as_path();
    if !models_dir.exists() {
        create_dir_all(models_dir).context("Failed to create models directory")?;
    }

    // Build HTTP client (may be unused in offline copy mode)
    let client = Client::builder()
        .user_agent("PolyScribe/0.1 (+https://github.com/)")
        .timeout(std::time::Duration::from_secs(600))
        .build()
        .context("Failed to build HTTP client")?;

    // Obtain manifest: env override or online fetch
    let models: Vec<ModelEntry> = if let Ok(manifest_path) = env::var("POLYSCRIBE_MODELS_MANIFEST") {
        let data = std::fs::read_to_string(&manifest_path)
            .with_context(|| format!("Failed to read manifest at {}", manifest_path))?;
        let mut list: Vec<ModelEntry> = serde_json::from_str(&data)
            .with_context(|| format!("Invalid JSON manifest: {}", manifest_path))?;
        // sort for stability
        list.sort_by(|a,b| a.name.cmp(&b.name));
        list
    } else {
        fetch_all_models(&client)?
    };

    // Map name -> entry for fast lookup
    let mut map: BTreeMap<String, ModelEntry> = BTreeMap::new();
    for m in models { map.insert(m.name.clone(), m); }

    // Scan local ggml-*.bin models
    let rd = std::fs::read_dir(models_dir)
        .with_context(|| format!("Failed to read models dir: {}", models_dir.display()))?;
    for entry in rd {
        let entry = entry?;
        let path = entry.path();
        if !path.is_file() { continue; }
        let fname = match path.file_name().and_then(|s| s.to_str()) { Some(s) => s.to_string(), None => continue };
        if !fname.starts_with("ggml-") || !fname.ends_with(".bin") { continue; }
        let model_name = fname.trim_start_matches("ggml-").trim_end_matches(".bin").to_string();

        if let Some(remote) = map.get(&model_name) {
            // If SHA256 available, verify and update if mismatch
            if let Some(expected) = &remote.sha256 {
                match compute_file_sha256_hex(&path) {
                    Ok(local_hash) => {
                        if local_hash.eq_ignore_ascii_case(expected) {
                            eprintln!("{} is up-to-date.", fname);
                            continue;
                        } else {
                            eprintln!(
                                "{} hash differs (local {}.. != remote {}..). Updating...",
                                fname,
                                &local_hash[..std::cmp::min(8, local_hash.len())],
                                &expected[..std::cmp::min(8, expected.len())]
                            );
                        }
                    }
                    Err(e) => {
                        eprintln!("Warning: failed hashing {}: {}. Re-downloading.", fname, e);
                    }
                }
                download_one_model(&client, models_dir, remote)?;
            } else if remote.size > 0 {
                match std::fs::metadata(&path) {
                    Ok(md) if md.len() == remote.size => {
                        eprintln!("{} appears up-to-date by size ({}).", fname, remote.size);
                        continue;
                    }
                    Ok(md) => {
                        eprintln!("{} size {} differs from remote {}. Updating...", fname, md.len(), remote.size);
                        download_one_model(&client, models_dir, remote)?;
                    }
                    Err(e) => {
                        eprintln!("Warning: stat failed for {}: {}. Updating...", fname, e);
                        download_one_model(&client, models_dir, remote)?;
                    }
                }
            } else {
                eprintln!("No remote hash/size for {}. Skipping.", fname);
            }
        } else {
            eprintln!("No remote metadata for {}. Skipping.", fname);
        }
    }

    Ok(())
}


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

    fn sha256_hex(data: &[u8]) -> String {
        use sha2::{Digest, Sha256};
        let mut hasher = Sha256::new();
        hasher.update(data);
        let out = hasher.finalize();
        let mut s = String::new();
        for b in out { s.push_str(&format!("{:02x}", b)); }
        s
    }

    #[test]
    fn test_update_local_models_offline_copy_and_manifest() {
        let tmp_models = tempdir().unwrap();
        let tmp_base = tempdir().unwrap();
        let tmp_manifest = tempdir().unwrap();

        // Prepare source model file content and hash
        let model_name = "tiny.en-q5_1";
        let src_path = tmp_base.path().join(format!("ggml-{}.bin", model_name));
        let new_content = b"new model content";
        fs::write(&src_path, new_content).unwrap();
        let expected_sha = sha256_hex(new_content);
        let expected_size = new_content.len() as u64;

        // Write a wrong existing local file to trigger update
        let local_path = tmp_models.path().join(format!("ggml-{}.bin", model_name));
        fs::write(&local_path, b"old content").unwrap();

        // Write manifest JSON
        let manifest_path = tmp_manifest.path().join("manifest.json");
        let manifest = serde_json::json!([
            {
                "name": model_name,
                "base": "tiny",
                "subtype": "en-q5_1",
                "size": expected_size,
                "sha256": expected_sha,
                "repo": "ggerganov/whisper.cpp"
            }
        ]);
        fs::write(&manifest_path, serde_json::to_string_pretty(&manifest).unwrap()).unwrap();

        // Set env vars to force offline behavior and directories
        unsafe {
            std::env::set_var("POLYSCRIBE_MODELS_MANIFEST", &manifest_path);
            std::env::set_var("POLYSCRIBE_MODELS_BASE_COPY_DIR", tmp_base.path());
            std::env::set_var("POLYSCRIBE_MODELS_DIR", tmp_models.path());
        }

        // Run update
        update_local_models().unwrap();

        // Verify local file equals source content
        let got = fs::read(&local_path).unwrap();
        assert_eq!(got, new_content);
    }

    #[test]
    #[cfg(debug_assertions)]
    fn test_models_dir_path_default_debug_and_env_override_models_mod() {
        // clear override
        unsafe { std::env::remove_var("POLYSCRIBE_MODELS_DIR"); }
        assert_eq!(super::models_dir_path(), std::path::PathBuf::from("models"));
        // override
        let tmp = tempfile::tempdir().unwrap();
        unsafe { std::env::set_var("POLYSCRIBE_MODELS_DIR", tmp.path()); }
        assert_eq!(super::models_dir_path(), tmp.path().to_path_buf());
        // cleanup
        unsafe { std::env::remove_var("POLYSCRIBE_MODELS_DIR"); }
    }

    #[test]
    #[cfg(not(debug_assertions))]
    fn test_models_dir_path_default_release_models_mod() {
        unsafe { std::env::remove_var("POLYSCRIBE_MODELS_DIR"); }
        assert_eq!(super::models_dir_path(), std::path::PathBuf::from("/usr/share/polyscribe/models"));
    }
}