use std::io;

use anyhow::{Context, Result, bail};
use libloading::Library;
use plugin_api::Plugin;
use tempfile::NamedTempFile;

use crate::LocatedPlugin;

pub struct LoadedPlugin {
    pub located: LocatedPlugin,
    pub plugin: Box<dyn Plugin>,
    // DO NOT MOVE THIS UP!
    // This is due to rust's dropping order!
    // If the library gets dropped (unloaded) before the plugin, a segfault will occur.
    pub lib: Library,
}

pub fn load(mut plugin: LocatedPlugin) -> Result<LoadedPlugin> {
    #[cfg(target_os = "linux")]
    let cdylib = plugin.so;

    #[cfg(target_os = "windows")]
    let cdylib = plugin.dll;

    #[cfg(target_os = "macos")]
    let cdylib = plugin.dylib;

    if !cdylib {
        bail!("unsupported platform");
    }

    #[cfg(target_os = "linux")]
    let cdylib = "plugin.so";

    #[cfg(target_os = "windows")]
    let cdylib = "plugin.dll";

    #[cfg(target_os = "macos")]
    let cdylib = "plugin.dylib";

    let mut tmp = NamedTempFile::new().context("failed creating temp file")?;
    {
        let mut entry = plugin.zip.by_name(cdylib).unwrap();
        io::copy(&mut entry, &mut tmp).context("failed copying cdylib to temp file")?;
    }

    unsafe {
        let lib =
            Library::new(tmp.path().display().to_string()).context("failed loading library")?;
        let ctor = lib
            .get::<unsafe extern "Rust" fn() -> Box<dyn Plugin>>(b"provide_plugin")
            .context("plugin does not have a provide_plugin function")?;
        let instance = ctor();

        Ok(LoadedPlugin {
            located: plugin,
            lib,
            plugin: instance,
        })
    }
}