use anyhow::{Context as _, Result, bail};
use log::{debug, info, warn};
use std::path::{Path, PathBuf};

/// Result of a successful publish operation.
#[derive(Debug)]
pub struct PublishResult {
    /// Path to the timestamped build directory containing the published assets.
    pub build_dir: PathBuf,
    /// Timestamp used for the build directory name.
    pub timestamp: String,
}

/// Publish built assets with atomic symlink switching.
///
/// # Arguments
/// * `base_dir` - Base witryna directory (e.g., /var/lib/witryna)
/// * `site_name` - The site name (already validated)
/// * `clone_dir` - Path to the cloned repository
/// * `public` - Relative path to built assets within `clone_dir` (e.g., "dist")
/// * `timestamp` - Timestamp string for the build directory (format: %Y%m%d-%H%M%S-%f)
///
/// # Errors
///
/// Returns an error if the source directory doesn't exist, the asset copy
/// fails, or the atomic symlink switch fails.
///
/// # Workflow
/// 1. Validate source directory exists
/// 2. Create timestamped build directory: {`base_dir}/builds/{site_name}/{timestamp`}
/// 3. Copy assets from {`clone_dir}/{public`}/ to the timestamped directory
/// 4. Atomic symlink switch: update {`base_dir}/builds/{site_name}/current`
pub async fn publish(
    base_dir: &Path,
    site_name: &str,
    clone_dir: &Path,
    public: &str,
    timestamp: &str,
) -> Result<PublishResult> {
    // 1. Construct source path and validate it exists
    let source_dir = clone_dir.join(public);
    if !source_dir.exists() {
        bail!("public directory does not exist");
    }
    if !source_dir.is_dir() {
        bail!("public path is not a directory");
    }

    // 2. Create build directory with provided timestamp
    let site_builds_dir = base_dir.join("builds").join(site_name);
    let build_dir = site_builds_dir.join(timestamp);
    let current_link = site_builds_dir.join("current");

    info!(
        "publishing assets: source={} destination={}",
        source_dir.display(),
        build_dir.display()
    );

    // 3. Create builds directory structure
    tokio::fs::create_dir_all(&site_builds_dir)
        .await
        .with_context(|| {
            format!(
                "failed to create builds directory: {}",
                site_builds_dir.display()
            )
        })?;

    // 4. Copy assets recursively
    copy_dir_contents(&source_dir, &build_dir)
        .await
        .context("failed to copy assets")?;

    // 5. Atomic symlink switch
    atomic_symlink_update(&build_dir, &current_link).await?;

    debug!(
        "publish completed: build_dir={} symlink={}",
        build_dir.display(),
        current_link.display()
    );

    Ok(PublishResult {
        build_dir,
        timestamp: timestamp.to_owned(),
    })
}

async fn copy_dir_contents(src: &Path, dst: &Path) -> Result<()> {
    tokio::fs::create_dir_all(dst)
        .await
        .with_context(|| format!("failed to create directory: {}", dst.display()))?;

    // Preserve source directory permissions
    let dir_metadata = tokio::fs::symlink_metadata(src).await?;
    tokio::fs::set_permissions(dst, dir_metadata.permissions())
        .await
        .with_context(|| format!("failed to set permissions on {}", dst.display()))?;

    let mut entries = tokio::fs::read_dir(src)
        .await
        .with_context(|| format!("failed to read directory: {}", src.display()))?;

    while let Some(entry) = entries.next_entry().await? {
        let entry_path = entry.path();
        let dest_path = dst.join(entry.file_name());

        // SEC-002: reject symlinks in build output to prevent symlink attacks
        let metadata = tokio::fs::symlink_metadata(&entry_path).await?;
        if metadata.file_type().is_symlink() {
            warn!("skipping symlink in build output: {}", entry_path.display());
            continue;
        }

        let file_type = entry.file_type().await?;

        if file_type.is_dir() {
            Box::pin(copy_dir_contents(&entry_path, &dest_path)).await?;
        } else {
            tokio::fs::copy(&entry_path, &dest_path)
                .await
                .with_context(|| {
                    format!(
                        "failed to copy {} to {}",
                        entry_path.display(),
                        dest_path.display()
                    )
                })?;
            // Preserve source file permissions
            tokio::fs::set_permissions(&dest_path, metadata.permissions())
                .await
                .with_context(|| format!("failed to set permissions on {}", dest_path.display()))?;
        }
    }

    Ok(())
}

/// Atomically update a symlink to point to a new target.
///
/// Uses the temp-symlink + rename pattern for atomicity:
/// 1. Create temp symlink: {`link_path}.tmp` -> target
/// 2. Rename temp to final: {`link_path}.tmp` -> {`link_path`}
///
/// The rename operation is atomic on POSIX filesystems.
///
/// # Errors
///
/// Returns an error if the temporary symlink cannot be created or the atomic rename fails.
pub async fn atomic_symlink_update(target: &Path, link_path: &Path) -> Result<()> {
    let temp_link = link_path.with_extension("tmp");

    // Remove any stale temp symlink from previous failed attempts
    let _ = tokio::fs::remove_file(&temp_link).await;

    // Create temporary symlink pointing to target
    tokio::fs::symlink(target, &temp_link)
        .await
        .with_context(|| "failed to create temporary symlink")?;

    // Atomically rename temp symlink to final location
    tokio::fs::rename(&temp_link, link_path)
        .await
        .with_context(|| "failed to atomically update symlink")?;

    Ok(())
}

#[cfg(test)]
#[allow(clippy::unwrap_used, clippy::indexing_slicing)]
mod tests {
    use super::*;
    use crate::test_support::{cleanup, temp_dir};
    use tokio::fs;

    fn test_timestamp() -> String {
        crate::time::format_build_timestamp(std::time::SystemTime::now())
    }

    #[tokio::test]
    async fn publish_copies_assets_to_timestamped_directory() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create source assets
        let source = clone_dir.join("dist");
        fs::create_dir_all(&source).await.unwrap();
        fs::write(source.join("index.html"), "<html>hello</html>")
            .await
            .unwrap();

        let timestamp = test_timestamp();
        let result = publish(&base_dir, "my-site", &clone_dir, "dist", &timestamp).await;

        assert!(result.is_ok(), "publish should succeed: {result:?}");
        let publish_result = result.unwrap();

        // Verify timestamp is used for build directory
        assert_eq!(publish_result.timestamp, timestamp);

        // Verify assets were copied
        let copied_file = publish_result.build_dir.join("index.html");
        assert!(copied_file.exists(), "copied file should exist");
        let content = fs::read_to_string(&copied_file).await.unwrap();
        assert_eq!(content, "<html>hello</html>");

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_creates_current_symlink() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create source assets
        let source = clone_dir.join("public");
        fs::create_dir_all(&source).await.unwrap();
        fs::write(source.join("file.txt"), "content").await.unwrap();

        let timestamp = test_timestamp();
        let result = publish(&base_dir, "test-site", &clone_dir, "public", &timestamp).await;

        assert!(result.is_ok(), "publish should succeed: {result:?}");
        let publish_result = result.unwrap();

        // Verify current symlink exists and points to build dir
        let current_link = base_dir.join("builds/test-site/current");
        assert!(current_link.exists(), "current symlink should exist");

        let link_target = fs::read_link(&current_link).await.unwrap();
        assert_eq!(link_target, publish_result.build_dir);

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_symlink_updated_on_second_publish() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create source assets
        let source = clone_dir.join("dist");
        fs::create_dir_all(&source).await.unwrap();
        fs::write(source.join("file.txt"), "v1").await.unwrap();

        // First publish
        let timestamp1 = "20260126-100000-000001".to_owned();
        let result1 = publish(&base_dir, "my-site", &clone_dir, "dist", &timestamp1).await;
        assert!(result1.is_ok());
        let publish1 = result1.unwrap();

        // Update source and publish again with different timestamp
        fs::write(source.join("file.txt"), "v2").await.unwrap();

        let timestamp2 = "20260126-100000-000002".to_owned();
        let result2 = publish(&base_dir, "my-site", &clone_dir, "dist", &timestamp2).await;
        assert!(result2.is_ok());
        let publish2 = result2.unwrap();

        // Verify symlink points to second build
        let current_link = base_dir.join("builds/my-site/current");
        let link_target = fs::read_link(&current_link).await.unwrap();
        assert_eq!(link_target, publish2.build_dir);

        // Verify both build directories still exist
        assert!(
            publish1.build_dir.exists(),
            "first build should still exist"
        );
        assert!(publish2.build_dir.exists(), "second build should exist");

        // Verify content is correct
        let content = fs::read_to_string(publish2.build_dir.join("file.txt"))
            .await
            .unwrap();
        assert_eq!(content, "v2");

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_missing_source_returns_error() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Don't create source directory

        let timestamp = test_timestamp();
        let result = publish(&base_dir, "my-site", &clone_dir, "nonexistent", &timestamp).await;

        assert!(result.is_err(), "publish should fail");
        let err = result.unwrap_err().to_string();
        assert!(err.contains("public directory does not exist"));

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_source_is_file_returns_error() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create a file instead of directory
        fs::write(clone_dir.join("dist"), "not a directory")
            .await
            .unwrap();

        let timestamp = test_timestamp();
        let result = publish(&base_dir, "my-site", &clone_dir, "dist", &timestamp).await;

        assert!(result.is_err(), "publish should fail");
        let err = result.unwrap_err().to_string();
        assert!(err.contains("public path is not a directory"));

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_nested_public_directory() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create nested source directory
        let source = clone_dir.join("build/output/dist");
        fs::create_dir_all(&source).await.unwrap();
        fs::write(source.join("app.js"), "console.log('hello')")
            .await
            .unwrap();

        let timestamp = test_timestamp();
        let result = publish(
            &base_dir,
            "my-site",
            &clone_dir,
            "build/output/dist",
            &timestamp,
        )
        .await;

        assert!(result.is_ok(), "publish should succeed: {result:?}");
        let publish_result = result.unwrap();

        // Verify file was copied
        let copied_file = publish_result.build_dir.join("app.js");
        assert!(copied_file.exists(), "copied file should exist");

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn publish_preserves_directory_structure() {
        let base_dir = temp_dir("publish-test").await;
        let clone_dir = temp_dir("publish-test").await;

        // Create source with subdirectories
        let source = clone_dir.join("public");
        fs::create_dir_all(source.join("css")).await.unwrap();
        fs::create_dir_all(source.join("js")).await.unwrap();
        fs::write(source.join("index.html"), "<html></html>")
            .await
            .unwrap();
        fs::write(source.join("css/style.css"), "body {}")
            .await
            .unwrap();
        fs::write(source.join("js/app.js"), "// app").await.unwrap();

        let timestamp = test_timestamp();
        let result = publish(&base_dir, "my-site", &clone_dir, "public", &timestamp).await;

        assert!(result.is_ok(), "publish should succeed: {result:?}");
        let publish_result = result.unwrap();

        // Verify structure preserved
        assert!(publish_result.build_dir.join("index.html").exists());
        assert!(publish_result.build_dir.join("css/style.css").exists());
        assert!(publish_result.build_dir.join("js/app.js").exists());

        cleanup(&base_dir).await;
        cleanup(&clone_dir).await;
    }

    #[tokio::test]
    async fn atomic_symlink_update_replaces_existing() {
        let temp = temp_dir("publish-test").await;

        // Create two target directories
        let target1 = temp.join("build-1");
        let target2 = temp.join("build-2");
        fs::create_dir_all(&target1).await.unwrap();
        fs::create_dir_all(&target2).await.unwrap();

        let link_path = temp.join("current");

        // Create initial symlink
        atomic_symlink_update(&target1, &link_path).await.unwrap();
        let link1 = fs::read_link(&link_path).await.unwrap();
        assert_eq!(link1, target1);

        // Update symlink
        atomic_symlink_update(&target2, &link_path).await.unwrap();
        let link2 = fs::read_link(&link_path).await.unwrap();
        assert_eq!(link2, target2);

        cleanup(&temp).await;
    }

    #[tokio::test]
    async fn copy_dir_contents_skips_symlinks() {
        let src = temp_dir("publish-test").await;
        let dst = temp_dir("publish-test").await;

        // Create a normal file
        fs::write(src.join("real.txt"), "hello").await.unwrap();

        // Create a symlink pointing outside the directory
        let outside = temp_dir("publish-test").await;
        fs::write(outside.join("secret.txt"), "secret")
            .await
            .unwrap();
        tokio::fs::symlink(outside.join("secret.txt"), src.join("link.txt"))
            .await
            .unwrap();

        // Run copy
        let dest = dst.join("output");
        copy_dir_contents(&src, &dest).await.unwrap();

        // Normal file should be copied
        assert!(dest.join("real.txt").exists(), "real file should be copied");
        let content = fs::read_to_string(dest.join("real.txt")).await.unwrap();
        assert_eq!(content, "hello");

        // Symlink should NOT be copied
        assert!(
            !dest.join("link.txt").exists(),
            "symlink should not be copied"
        );

        cleanup(&src).await;
        cleanup(&dst).await;
        cleanup(&outside).await;
    }

    #[tokio::test]
    async fn copy_dir_contents_preserves_permissions() {
        use std::os::unix::fs::PermissionsExt;

        let src = temp_dir("publish-test").await;
        let dst = temp_dir("publish-test").await;

        // Create a file with executable permissions (0o755)
        fs::write(src.join("script.sh"), "#!/bin/sh\necho hi")
            .await
            .unwrap();
        let mut perms = fs::metadata(src.join("script.sh"))
            .await
            .unwrap()
            .permissions();
        perms.set_mode(0o755);
        fs::set_permissions(src.join("script.sh"), perms)
            .await
            .unwrap();

        // Create a file with restrictive permissions (0o644)
        fs::write(src.join("data.txt"), "data").await.unwrap();

        let dest = dst.join("output");
        copy_dir_contents(&src, &dest).await.unwrap();

        // Verify executable permission preserved
        let copied_perms = fs::metadata(dest.join("script.sh"))
            .await
            .unwrap()
            .permissions();
        assert_eq!(
            copied_perms.mode() & 0o777,
            0o755,
            "executable permissions should be preserved"
        );

        cleanup(&src).await;
        cleanup(&dst).await;
    }
}