// I/O module — open and save CAD documents.
//
// All file reading/writing goes through acadrust.
// Default save format: DWG (AC1032 / R2018+).

use acadrust::io::dwg::DwgReader;
use acadrust::{CadDocument, DwgWriter, DxfReader, DxfWriter};
use std::path::{Path, PathBuf};

// ── Open ──────────────────────────────────────────────────────────────────

/// Show a file-open dialog and load the selected DWG or DXF file.
/// Returns `(filename, path, document)` or an error string.
pub async fn pick_and_open() -> Result<(String, PathBuf, CadDocument), String> {
    let handle = rfd::AsyncFileDialog::new()
        .set_title("Open CAD file")
        .add_filter("CAD Files", &["dwg", "dxf", "DWG", "DXF"])
        .add_filter("DWG Files", &["dwg", "DWG"])
        .add_filter("DXF Files", &["dxf", "DXF"])
        .add_filter("All Files", &["*"])
        .pick_file()
        .await;

    let handle = match handle {
        Some(h) => h,
        None => return Err("Cancelled".into()),
    };

    let path = handle.path().to_path_buf();
    open_path(path).await
}

/// Load a CAD file from a known path (used by recent files).
pub async fn open_path(path: PathBuf) -> Result<(String, PathBuf, CadDocument), String> {
    let name = path
        .file_name()
        .map(|n| n.to_string_lossy().into_owned())
        .unwrap_or_else(|| "unknown".into());
    let doc = load_file(&path)?;
    Ok((name, path, doc))
}

/// Load a DWG or DXF file directly from a path (auto-detect by extension).
pub fn load_file(path: &Path) -> Result<CadDocument, String> {
    let ext = path
        .extension()
        .map(|e| e.to_string_lossy().to_lowercase())
        .unwrap_or_default();

    match ext.as_str() {
        "dwg" => {
            let mut reader = DwgReader::from_file(path).map_err(|e| e.to_string())?;
            reader.read().map_err(|e| e.to_string())
        }
        "dxf" => DxfReader::from_file(path)
            .map_err(|e| e.to_string())?
            .read()
            .map_err(|e| e.to_string()),
        _ => Err(format!("Unsupported file format: .{ext}")),
    }
}

// ── Save dialog ───────────────────────────────────────────────────────────

/// Show a save-file dialog listing all DWG and DXF version filters.
/// DWG versions appear first; format is auto-detected from the returned extension.
pub async fn pick_save_path() -> Option<PathBuf> {
    let dwg_filters: &[(&str, &[&str])] = &[
        ("DWG Files (2018)", &["dwg"]),
        ("DWG Files (2013)", &["dwg"]),
        ("DWG Files (2010)", &["dwg"]),
        ("DWG Files (2007)", &["dwg"]),
        ("DWG Files (2004)", &["dwg"]),
        ("DWG Files (2000)", &["dwg"]),
        ("DWG Files (R14)", &["dwg"]),
        ("DWG Files (R13)", &["dwg"]),
    ];
    let dxf_filters: &[(&str, &[&str])] = &[
        ("DXF Files (2018)", &["dxf"]),
        ("DXF Files (2013)", &["dxf"]),
        ("DXF Files (2010)", &["dxf"]),
        ("DXF Files (2007)", &["dxf"]),
        ("DXF Files (2004)", &["dxf"]),
        ("DXF Files (2000)", &["dxf"]),
        ("DXF Files (R14)", &["dxf"]),
        ("DXF Files (R13)", &["dxf"]),
    ];

    let mut dlg = rfd::AsyncFileDialog::new()
        .set_title("Save As")
        .set_file_name("drawing.dwg");
    for (label, exts) in dwg_filters.iter().chain(dxf_filters.iter()) {
        dlg = dlg.add_filter(*label, *exts);
    }
    dlg.save_file().await.map(|h| h.path().to_path_buf())
}

// ── Save ──────────────────────────────────────────────────────────────────

/// Save the document to the given path.
/// Format is auto-detected from the extension (dwg / dxf).
pub fn save(doc: &CadDocument, path: &Path) -> Result<(), String> {
    let ext = path
        .extension()
        .map(|e| e.to_string_lossy().to_lowercase())
        .unwrap_or_default();
    match ext.as_str() {
        "dxf" => save_dxf(doc, path),
        _ => save_dwg(doc, path),
    }
}

pub fn save_dwg(doc: &CadDocument, path: &Path) -> Result<(), String> {
    DwgWriter::write_to_file(path, doc).map_err(|e| e.to_string())
}

pub fn save_dxf(doc: &CadDocument, path: &Path) -> Result<(), String> {
    DxfWriter::new(doc)
        .write_to_file(path)
        .map_err(|e| e.to_string())
}