//! Demonstrates how to apply a parsed diff to a file

use patch::{Line, Patch};

fn apply(diff: Patch, old: &str) -> String {
    let old_lines = old.lines().collect::<Vec<&str>>();
    let mut out: Vec<&str> = vec![];
    let mut old_line = 0;
    for hunk in diff.hunks {
        while old_line < hunk.old_range.start - 1 {
            out.push(old_lines[old_line as usize]);
            old_line += 1;
        }
        old_line += hunk.old_range.count;
        for line in hunk.lines {
            match line {
                Line::Add(s) | Line::Context(s) => out.push(s),
                Line::Remove(_) => {}
            }
        }
    }
    out.join("\n")
}

static LAO: &str = "\
The Way that can be told of is not the eternal Way;
The name that can be named is not the eternal name.
The Nameless is the origin of Heaven and Earth;
The Named is the mother of all things.
Therefore let there always be non-being,
  so we may see their subtlety,
And let there always be being,
  so we may see their outcome.
The two are the same,
But after they are produced,
  they have different names.
";

static RAW_DIFF: &str = "\
--- lao 2002-02-21 23:30:39.942229878 -0800
+++ tzu 2002-02-21 23:30:50.442260588 -0800
@@ -1,7 +1,6 @@
-The Way that can be told of is not the eternal Way;
-The name that can be named is not the eternal name.
 The Nameless is the origin of Heaven and Earth;
-The Named is the mother of all things.
+The named is the mother of all things.
+
 Therefore let there always be non-being,
   so we may see their subtlety,
 And let there always be being,
@@ -9,3 +8,6 @@
 The two are the same,
 But after they are produced,
   they have different names.
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
";

fn main() {
    let diff = Patch::from_single(RAW_DIFF).unwrap();
    let new = apply(diff, LAO);
    println!("should be tzu:\n\n{}", new);
}