Overhaul file erorr handling

src/files/error.rs

@@ -0,0 +1,79 @@
+use std::path::PathBuf;
+use std::{io, result};
+
+use super::parse;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Could not resolve {path}: {error}")]
+    ResolvePath { path: PathBuf, error: io::Error },
+    #[error("Could not load {file}: {error}")]
+    ReadFile { file: PathBuf, error: io::Error },
+    #[error("Could not write {file}: {error}")]
+    WriteFile { file: PathBuf, error: io::Error },
+    #[error("Could not resolve timezone {timezone}: {error}")]
+    ResolveTz { timezone: String, error: io::Error },
+    #[error("Could not determine local timezone: {error}")]
+    LocalTz { error: io::Error },
+    #[error("{0}")]
+    Parse(#[from] parse::Error),
+    #[error("{file1} has time zone {tz1} but {file2} has time zone {tz2}")]
+    TzConflict {
+        file1: PathBuf,
+        tz1: String,
+        file2: PathBuf,
+        tz2: String,
+    },
+    #[error("Not a task")]
+    NotATask(Vec<usize>),
+}
+
+impl Error {
+    pub fn print(self) {
+        match self {
+            Error::ResolvePath { path, error } => {
+                eprintln!("Could not resolve path {:?}:", path);
+                eprintln!("  {}", error);
+            }
+            Error::ReadFile { file, error } => {
+                eprintln!("Could not read file {:?}:", file);
+                eprintln!("  {}", error);
+            }
+            Error::WriteFile { file, error } => {
+                eprintln!("Could not write file {:?}:", file);
+                eprintln!("  {}", error);
+            }
+            Error::ResolveTz { timezone, error } => {
+                eprintln!("Could not resolve time zone {}:", timezone);
+                eprintln!("  {}", error);
+            }
+            Error::LocalTz { error } => {
+                eprintln!("Could not determine local timezone:");
+                eprintln!("  {}", error);
+            }
+            Error::Parse(error) => eprintln!("{}", error),
+            Error::TzConflict {
+                file1,
+                tz1,
+                file2,
+                tz2,
+            } => {
+                eprintln!("Time zone conflict:");
+                eprintln!("  {:?} has time zone {}", file1, tz1);
+                eprintln!("  {:?} has time zone {}", file2, tz2);
+            }
+            Error::NotATask(numbers) => {
+                if numbers.is_empty() {
+                    eprintln!("Not a task.");
+                } else if numbers.len() == 1 {
+                    eprintln!("{} is not a task.", numbers[0]);
+                } else {
+                    let numbers = numbers.iter().map(|n| n.to_string()).collect::<Vec<_>>();
+                    eprintln!("{} are not tasks.", numbers.join(", "));
+                }
+            }
+        }
+    }
+}
+
+pub type Result<T> = result::Result<T, Error>;