added conflict solver

src/conflict_resolver.rs

@@ -0,0 +1,70 @@
+use std::{collections::HashMap, path::PathBuf};
+
+use crate::{Mod, ModFile};
+
+pub struct ConflictSolver<'a> {
+    files: HashMap<PathBuf, (&'a ModFile, &'a Mod)>,
+}
+
+#[derive(Debug)]
+pub struct Conflict<'a> {
+    rhs_mod: &'a Mod,
+    lhs_mod: &'a Mod,
+    rhs_file: &'a ModFile,
+    lhs_file: &'a ModFile,
+}
+
+impl<'a> ConflictSolver<'a> {
+    pub fn new() -> Self {
+        Self {
+            files: HashMap::new(),
+        }
+    }
+
+    pub fn add_file(&mut self, file: &'a ModFile, from_mod: &'a Mod) -> Option<Conflict<'a>> {
+        let path = &file.dest;
+        match self.files.get(path) {
+            Some((current_file, current_file_mod)) => {
+                if from_mod == *current_file_mod {
+                    // File from the same mod
+                    // Check internal priority
+                    if file.internal_priority > current_file.internal_priority {
+                        self.files.insert(path.to_owned(), (file, from_mod));
+                        return None;
+                    }
+
+                    if file.internal_priority == current_file.internal_priority {
+                        // Same prio. We got a conflict.
+
+                        return Some(Conflict {
+                            rhs_mod: from_mod,
+                            lhs_mod: current_file_mod,
+                            rhs_file: file,
+                            lhs_file: current_file,
+                        });
+                    }
+                }
+
+                if from_mod.priority > current_file_mod.priority {
+                    self.files.insert(path.to_owned(), (file, from_mod));
+                    return None;
+                }
+
+                if from_mod.priority == current_file_mod.priority {
+                    // Different mod but priority the same. We got a conflict.
+                    return Some(Conflict {
+                        rhs_mod: from_mod,
+                        lhs_mod: current_file_mod,
+                        rhs_file: file,
+                        lhs_file: current_file,
+                    });
+                }
+            }
+            None => {
+                self.files.insert(path.to_owned(), (file, from_mod));
+            }
+        }
+
+        None
+    }
+}