use anyhow::{Context, Result};
use sha2::{Digest, Sha256};
use std::{collections::HashMap, path::Path};
use klog_types::FilesMetaResponse;

pub async fn upload_changed(base_url: &str, token: &str, folder: &Path) -> Result<Vec<String>> {
    let base_url = base_url.trim_end_matches('/');
    let client = reqwest::Client::new();

    let remote: FilesMetaResponse = client
        .get(format!("{base_url}/files"))
        .bearer_auth(token)
        .send()
        .await
        .context("GET /files request failed")?
        .error_for_status()
        .context("GET /files returned error status")?
        .json()
        .await
        .context("GET /files response parse failed")?;

    let remote_hashes: HashMap<String, String> = remote
        .files
        .into_iter()
        .map(|f| (f.filename, f.sha256))
        .collect();

    let mut uploaded = Vec::new();
    let mut entries = tokio::fs::read_dir(folder)
        .await
        .with_context(|| format!("Cannot read folder: {}", folder.display()))?;

    while let Some(entry) = entries.next_entry().await? {
        if !entry.file_type().await?.is_file() {
            continue;
        }
        let filename = entry.file_name().to_string_lossy().to_string();
        let data = tokio::fs::read(entry.path()).await?;
        let local_hash = hex::encode(Sha256::digest(&data));

        let needs_upload = remote_hashes
            .get(&filename)
            .map_or(true, |h| h != &local_hash);

        if !needs_upload {
            continue;
        }

        let part = reqwest::multipart::Part::bytes(data).file_name(filename.clone());
        let form = reqwest::multipart::Form::new().part("file", part);
        client
            .post(format!("{base_url}/files"))
            .bearer_auth(token)
            .multipart(form)
            .send()
            .await
            .with_context(|| format!("Upload failed for {filename}"))?
            .error_for_status()
            .with_context(|| format!("Upload error status for {filename}"))?;

        uploaded.push(filename);
    }

    Ok(uploaded)
}