1 files changed, 129 insertions, 0 deletions
diff --git a/lib/src/file/source/file.rs b/lib/src/file/source/file.rs
new file mode 100644
index 0000000..124b7dd
--- /dev/null
+++ b/lib/src/file/source/file.rs
@@ -0,0 +1,129 @@
+use std::str::FromStr;
+use std::result;
+use std::error::Error;
+
+use std::path::{PathBuf, Path};
+use std::io::{self, Read};
+use std::fs;
+use std::env;
+
+use source::Source;
+use super::{FileFormat, FileSource};
+
+/// Describes a file sourced from a file
+pub struct FileSourceFile {
+    /// Basename of configuration file
+    name: String,
+
+    /// Directory where configuration file is found
+    /// When not specified, the current working directory (CWD) is considered
+    path: Option<String>,
+}
+
+impl FileSourceFile {
+    pub fn new(name: &str) -> FileSourceFile {
+        FileSourceFile {
+            name: name.into(),
+            path: None,
+        }
+    }
+
+    fn find_file(&self, format_hint: Option<FileFormat>) -> Result<PathBuf, Box<Error>> {
+        // Build expected configuration file
+        let mut basename = PathBuf::new();
+        let extensions = format_hint.unwrap().extensions();
+
+        if let Some(ref path) = self.path {
+            basename.push(path.clone());
+        }
+
+        basename.push(self.name.clone());
+
+        // Find configuration file (algorithm similar to .git detection by git)
+        let mut dir = env::current_dir()?;
+        let mut filename = dir.as_path().join(basename.clone());
+
+        loop {
+            for ext in &extensions {
+                filename.set_extension(ext);
+
+                if filename.is_file() {
+                    // File exists and is a file
+                    return Ok(filename);
+                }
+            }
+
+            // Not found.. travse up via the dir
+            if !dir.pop() {
+                // Failed to find the configuration file
+                return Err(Box::new(io::Error::new(io::ErrorKind::NotFound,
+                                            format!("configuration file \"{}\" not found",
+                                                    basename.to_string_lossy()))
+                ));
+            }
+        }
+    }
+}
+
+impl FileSource for FileSourceFile {
+    fn resolve(&self, format_hint: Option<FileFormat>) -> Result<(Option<String>, String), Box<Error>> {
+        // Find file
+        let filename = self.find_file(format_hint)?;
+
+        // Attempt to use a relative path for the URI
+        let base = env::current_dir()?;
+        let uri = match path_relative_from(&filename, &base) {
+            Some(value) => value,
+            None => filename.clone(),
+        };
+
+        // Read contents from file
+        let mut file = fs::File::open(filename.clone())?;
+        let mut text = String::new();
+        file.read_to_string(&mut text)?;
+
+        Ok((Some(uri.to_string_lossy().into_owned()), text))
+    }
+}
+
+// TODO: This should probably be a crate
+// https://github.com/rust-lang/rust/blob/master/src/librustc_trans/back/rpath.rs#L128
+fn path_relative_from(path: &Path, base: &Path) -> Option<PathBuf> {
+    use std::path::Component;
+
+    if path.is_absolute() != base.is_absolute() {
+        if path.is_absolute() {
+            Some(PathBuf::from(path))
+        } else {
+            None
+        }
+    } else {
+        let mut ita = path.components();
+        let mut itb = base.components();
+        let mut comps: Vec<Component> = vec![];
+        loop {
+            match (ita.next(), itb.next()) {
+                (None, None) => break,
+                (Some(a), None) => {
+                    comps.push(a);
+                    comps.extend(ita.by_ref());
+                    break;
+                }
+                (None, _) => comps.push(Component::ParentDir),
+                (Some(a), Some(b)) if comps.is_empty() && a == b => (),
+                (Some(a), Some(b)) if b == Component::CurDir => comps.push(a),
+                (Some(_), Some(b)) if b == Component::ParentDir => return None,
+                (Some(a), Some(_)) => {
+                    comps.push(Component::ParentDir);
+                    for _ in itb {
+                        comps.push(Component::ParentDir);
+                    }
+                    comps.push(a);
+                    comps.extend(ita.by_ref());
+                    break;
+                }
+            }
+        }
+        Some(comps.iter().map(|c| c.as_os_str()).collect())
+    }
+}