use eyre::{Result, format_err};
use log::info;
use std::path::Path;
use tokio::fs;

use crate::{base64_decode, File};

pub async fn files(files: &[File], root: &str, dry_run: bool) -> Result<()> {
    for f in files {
        if let Err(e) = file(f, root, dry_run).await {
            return Err(format_err!("{}: {e}", f.path))
        }
    }
    Ok(())
}

pub async fn file(file: &File, root: &str, dry_run: bool) -> Result<()> {
        let path = chroot(root, &file.path);
        let path = Path::new(&path);

        if !dry_run && let Some(parent) = path.parent() {
            fs::create_dir_all(parent).await?;
        }

        use crate::{FileKind as K, FilePart as P};
        match file.kind().as_ref() {
            K::Skip => {
                info!("{}: kind is skip", file.path);
                return Ok(())
            },
            K::Content(content) => {
                if dry_run {
                    info!(
                        "would create {} ({} bytes from content)",
                        file.path,
                        content.len()
                    );
                } else {
                    fs::write(path, content.as_bytes()).await?;
                }
            }
            K::Content64(content) => {
                let content = base64_decode(content)?;
                if dry_run {
                    info!(
                        "would create {} ({} bytes from content64)",
                        file.path,
                        content.len()
                    );
                } else {
                    fs::write(path, content).await?
                }
            }
            K::Parts(parts) => {
                let mut assembly = Vec::new();
                for part in parts {
                    match part {
                        P::Content(content) => assembly.extend(content.as_bytes()),
                        P::Content64(content) => assembly.extend(base64_decode(content)?),
                    }
                }
                if dry_run {
                    info!(
                        "would create {} ({} bytes from parts)",
                        file.path,
                        assembly.len()
                    );
                } else {
                    fs::write(path, assembly).await?
                }
            }
            K::Dir => {
                if dry_run {
                    info!("would create {} (directory)", file.path);
                } else {
                    fs::create_dir(path).await?;
                }
            }
            K::Symlink(tgt) => {
                if dry_run {
                    info!("would create {} (symlink to {})", file.path, tgt);
                } else {
                    let _ = fs::remove_file(path).await; // we're ln --force
                    fs::symlink(tgt, path).await?;
                }
            }
        }

        if dry_run {
            return Ok(());
        }

        if file.is_symlink() {
             set_perms(path, file.mode).await?;
        }

        info!("created {}", file.path);
        Ok(())
    }

pub async fn set_perms(path: impl AsRef<Path>, mode: Option<u32>) -> std::io::Result<()> {
    if let Some(mode) = mode.filter(|m| *m != 0) {
        use std::os::unix::fs::PermissionsExt;
        let mode = std::fs::Permissions::from_mode(mode);
        fs::set_permissions(path, mode).await?;
    }
    Ok(())
}

pub fn chroot(root: &str, path: &str) -> String {
    format!("{root}/{}", path.trim_start_matches(|c| c == '/'))
}