prompt: add --fd-output (-f) & --output (-o) options

src/cmd/prompt.rs

@@ -1,20 +1,33 @@
 static USAGE: &str = r#"
-Open a file dialog to pick a file as input.
+Open a file dialog to pick a file as input or save to an output file.
 
 For example to pick a single file as input to qsv stats using a file dialog, we can
 pipe into qsv stats using qsv prompt:
 
 qsv prompt | qsv stats
 
+If you want to save the output of a command to a file using a save file dialog, you
+may pipe into qsv prompt but make sure you include the --fd-output (or -f) flag:
+
+qsv prompt | qsv stats | qsv prompt --fd-output
+
+Note that the save file dialog (output) may be shown first before the input dialog.
+
 For examples, see https://github.com/jqnatividad/qsv/blob/master/tests/test_prompt.rs.
 
 Usage:
     qsv prompt [options]
     qsv prompt --help
 
-    Common options:
+prompt options:
+    -f, --fd-output        Write output to a file by using a save file dialog.
+                           Used when piping into qsv prompt.
+
+Common options:
     -h, --help             Display this message
     -n, --no-headers       When set, does not include headers in output.
+    -o, --output <file>    Write output to <file> without showing a save dialog.
+
 "#;
 
 use rfd::FileDialog;
@@ -23,37 +36,75 @@ use crate::{config::Config, util, CliResult, Deserialize};
 
 #[derive(Deserialize)]
 struct Args {
+    flag_fd_output:  bool,
     flag_no_headers: bool,
+    flag_output:     Option<String>,
+}
+
+fn write_to_file(
+    args: &Args,
+    input_path: Option<String>,
+    output_path: Option<String>,
+) -> CliResult<()> {
+    let rconfig = Config::new(&input_path).no_headers(args.flag_no_headers);
+    let mut rdr = rconfig.reader()?;
+    let mut wtr = Config::new(&output_path).writer()?;
+    if !rconfig.no_headers {
+        rconfig.write_headers(&mut rdr, &mut wtr)?;
+    }
+    let mut record = csv::ByteRecord::new();
+
+    while rdr.read_byte_record(&mut record)? {
+        wtr.write_byte_record(&record)?;
+    }
+
+    wtr.flush()?;
+    Ok(())
 }
 
 pub fn run(argv: &[&str]) -> CliResult<()> {
     let args: Args = util::get_args(USAGE, argv)?;
-    if let Some(input_path) = FileDialog::new().set_directory("/").pick_file() {
-        if let Some(input_path_str) = input_path.to_str() {
-            let rconfig =
-                Config::new(&Some(input_path_str.to_string())).no_headers(args.flag_no_headers);
-            let mut rdr = rconfig.reader()?;
-            let mut wtr = Config::new(&None).writer()?;
-            if !rconfig.no_headers {
-                rconfig.write_headers(&mut rdr, &mut wtr)?;
-            }
-            let mut record = csv::ByteRecord::new();
-
-            while rdr.read_byte_record(&mut record)? {
-                wtr.write_byte_record(&record)?;
-            }
-
-            wtr.flush()?;
+    if args.flag_fd_output && args.flag_output.is_some() {
+        return fail_incorrectusage_clierror!(
+            "Cannot use --fd-output (-f) and --output (-o) together, choose one."
+        );
+    }
+    if !args.flag_fd_output && args.flag_output.is_none() {
+        if let Some(input_path) = FileDialog::new().set_directory("/").pick_file() {
+            if let Some(input_path_str) = input_path.to_str() {
+                write_to_file(&args, Some(input_path_str.to_string()), None)?;
+            } else {
+                return fail_clierror!(
+                    "Error while running qsv prompt. Perhaps the path to the file is not valid \
+                     unicode?"
+                );
+            };
         } else {
             return fail_clierror!(
-                "Error while running qsv prompt. Perhaps the path to the file is not valid \
-                 unicode?"
+                "Error while running qsv prompt. Perhaps you did not select a file for input?"
             );
         };
-    } else {
-        return fail_clierror!(
-            "Error while running qsv prompt. Perhaps you did not select a file?"
-        );
-    };
+    }
+    // If fd_output then write to output using save file
+    else if args.flag_fd_output {
+        if let Some(output_path) = FileDialog::new().set_directory("/").save_file() {
+            if let Some(output_path_str) = output_path.to_str() {
+                write_to_file(&args, None, Some(output_path_str.to_string()))?;
+            } else {
+                return fail_clierror!(
+                    "Error while running qsv prompt. Perhaps the path to the file is not valid \
+                     unicode?"
+                );
+            };
+        } else {
+            return fail_clierror!(
+                "Error while running qsv prompt. Perhaps you did not select a file for output?"
+            );
+        }
+    }
+    // If output then write to output and skip input path pick file
+    else {
+        write_to_file(&args, None, args.flag_output.clone())?;
+    }
     Ok(())
 }