use crate::host_bridge::file_payloads::{import_image_file_payload, import_image_mime_type};
use crate::shell::events::host_bridge_event_script;
use crate::shell::lifecycle::log_desktop_host_event_result;
use serde_json::Value;
use std::path::PathBuf;
use tauri::{DragDropEvent, WebviewWindow, WindowEvent};

fn first_valid_desktop_image_drop_payload(
    paths: &[PathBuf],
    position: (i32, i32),
) -> Option<Value> {
    paths.iter().find_map(|path| {
        if !path.is_file() || import_image_mime_type(path).is_none() {
            return None;
        }

        match import_image_file_payload(path.clone(), "dropped", Some(position)) {
            Ok(payload) => Some(payload),
            Err(_error) => {
                log_desktop_image_drop_payload_failure();
                None
            }
        }
    })
}

fn log_desktop_image_drop_payload_failure() -> bool {
    eprintln!("desktop host event failed for file.imageDropped.payload");
    false
}

fn normalize_desktop_drop_position(x: f64, y: f64) -> (i32, i32) {
    (x.round().max(0.0) as i32, y.round().max(0.0) as i32)
}

fn emit_desktop_image_drop_event(
    window: &WebviewWindow,
    paths: &[PathBuf],
    position: (i32, i32),
) -> tauri::Result<()> {
    let Some(payload) = first_valid_desktop_image_drop_payload(paths, position) else {
        return Ok(());
    };
    let script =
        host_bridge_event_script("file.imageDropped", payload).map_err(tauri::Error::Json)?;

    window.eval(script)
}

pub(crate) fn register_desktop_file_drop_events(window: &WebviewWindow) {
    let drop_window = window.clone();
    window.on_window_event(move |event| {
        if let WindowEvent::DragDrop(DragDropEvent::Drop { paths, position }) = event {
            let drop_position = normalize_desktop_drop_position(position.x, position.y);
            log_desktop_host_event_result(
                "file.imageDropped",
                emit_desktop_image_drop_event(&drop_window, paths, drop_position),
            );
        }
    });
}

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

    fn png_bytes() -> Vec<u8> {
        vec![0x89, b'P', b'N', b'G', 0x0d, 0x0a, 0x1a, 0x0a, 0, 0, 0, 0]
    }

    #[test]
    fn image_drop_skips_disguised_image_before_valid_image() {
        let invalid_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-invalid-{}.png",
            std::process::id()
        ));
        let valid_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-valid-{}.png",
            std::process::id()
        ));
        fs::write(&invalid_path, b"text").expect("write invalid drop image");
        fs::write(&valid_path, png_bytes()).expect("write valid drop image");

        let payload = first_valid_desktop_image_drop_payload(
            &[invalid_path.clone(), valid_path.clone()],
            (7, 9),
        )
        .expect("valid image drop payload");

        assert_eq!(
            payload["fileName"],
            valid_path.file_name().unwrap().to_str().unwrap()
        );
        assert_eq!(payload["position"], serde_json::json!({ "x": 7, "y": 9 }));

        fs::remove_file(invalid_path).expect("remove invalid drop image");
        fs::remove_file(valid_path).expect("remove valid drop image");
    }

    #[test]
    fn image_drop_logs_invalid_candidate_then_uses_next_valid_image() {
        let disguised_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-disguised-{}.png",
            std::process::id()
        ));
        let valid_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-valid-after-error-{}.png",
            std::process::id()
        ));
        fs::write(&disguised_path, b"text").expect("write disguised drop image");
        fs::write(&valid_path, png_bytes()).expect("write valid drop image");

        let payload = first_valid_desktop_image_drop_payload(
            &[disguised_path.clone(), valid_path.clone()],
            (11, 13),
        )
        .expect("valid image drop payload after invalid candidate");

        assert_eq!(
            payload["fileName"],
            valid_path.file_name().unwrap().to_str().unwrap()
        );
        assert_eq!(payload["position"], serde_json::json!({ "x": 11, "y": 13 }));

        fs::remove_file(disguised_path).expect("remove disguised drop image");
        fs::remove_file(valid_path).expect("remove valid drop image");
    }

    #[test]
    fn image_drop_payload_failure_reports_failure() {
        assert!(!log_desktop_image_drop_payload_failure());
    }

    #[test]
    fn image_drop_payload_failure_logs_stable_label_only() {
        assert!(!log_desktop_image_drop_payload_failure());
    }

    #[test]
    fn image_drop_without_valid_image_does_not_emit_payload() {
        let text_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-text-{}.txt",
            std::process::id()
        ));
        let directory_path = std::env::temp_dir().join(format!(
            "genarrative-desktop-drop-directory-{}",
            std::process::id()
        ));
        fs::write(&text_path, b"not an image").expect("write text drop file");
        fs::create_dir_all(&directory_path).expect("create drop directory");

        let payload = first_valid_desktop_image_drop_payload(
            &[directory_path.clone(), text_path.clone()],
            (3, 5),
        );

        assert_eq!(payload, None);

        fs::remove_file(text_path).expect("remove text drop file");
        fs::remove_dir(directory_path).expect("remove drop directory");
    }

    #[test]
    fn desktop_drop_position_is_rounded_and_clamped_to_window_bounds() {
        assert_eq!(normalize_desktop_drop_position(12.4, 24.6), (12, 25));
        assert_eq!(normalize_desktop_drop_position(-4.2, -0.6), (0, 0));
    }
}