1 files changed, 137 insertions, 0 deletions

diff --git a/src/funcs/find_latest_patch.rs b/src/funcs/find_latest_patch.rs
new file mode 100644
index 0000000..717d6c1
--- /dev/null
+++ b/src/funcs/find_latest_patch.rs
@@ -0,0 +1,137 @@
+use std::path::PathBuf;
+
+use nostr::{ Event };
+
+use crate::{ngit_tag::{tag_is_branch, tag_extract_value, tag_is_commit}, branch_refs::BranchRefs, utils::load_event, kind::Kind};
+
+/// finds latest patch that needs applying. It might not be the latest created_at date if an earlier patch was 'merged' more recently
+pub fn find_latest_patch(
+    branch_id: &String,
+    patch_events:&Vec<Event>,
+    merges_into_branch: &Vec<Event>,
+    branch_refs:&BranchRefs,
+    repo_dir_path: &PathBuf,
+) -> Option<Event> {
+
+    // ensure only patch events make it into patch_events - we cant rely on relays for this
+    let patch_events:Vec<Event> = patch_events.iter().filter(|p|
+        // kind is patch
+        p.kind == nostr_sdk::Kind::Custom(u64::from(Kind::Patch))
+    ).map(|p|p.clone()).collect();
+
+    let directly_authorised_patches: Vec<Event> = patch_events.iter().filter(|p|
+        // kind is patch
+        p.kind == nostr_sdk::Kind::Custom(u64::from(Kind::Patch))
+        // on branch
+        && p.tags.iter().any(
+            |t|tag_is_branch(t)
+            && tag_extract_value(t) == branch_id.clone()
+        )
+        // authorized
+        && match &branch_refs.is_authorized(Some(&branch_id), &p.pubkey) {
+            None => { false },
+            Some(is_authorized) => { is_authorized.clone() }
+        }
+    ).map(|p|p.clone()).collect();
+
+    let latest_authorized_patch = find_latest_event(&directly_authorised_patches);
+
+    let authorised_merges: Vec<Event> = merges_into_branch.iter().filter(|m|
+        // kind is merge
+        m.kind == nostr_sdk::Kind::Custom(u64::from(Kind::Merge))
+        // into branch
+        && m.tags.iter().any(
+            |t|tag_is_branch(t)
+            && tag_extract_value(t) == branch_id.clone()
+        )
+        // merge authorized
+        && match &branch_refs.is_authorized(Some(&branch_id), &m.pubkey) {
+            None => { false },
+            Some(is_authorized) => { is_authorized.clone() }
+        }
+    ).map(|p|p.clone()).collect();
+
+    let latest_authorised_merge = find_latest_event(&authorised_merges);
+
+    // find latest patch
+
+    match latest_authorised_merge {
+        // no merge - return patch or None
+        None => latest_authorized_patch,
+        Some(m) => {
+            match latest_authorized_patch {
+                // merge but no patch, return the patch related to the merge
+                None => {
+                    Some(get_merge_patch(
+                        &m,
+                        &patch_events,
+                        repo_dir_path,
+                    ))
+                },
+                // a merge and a patch
+                Some(p) => {
+                    // return the patch if it is later than merge
+                    if m.created_at < p.created_at {
+                        Some(p.clone())
+                    }
+                    // return the patch related to the merge if the merge is later
+                    else {
+                        Some(get_merge_patch(
+                            &m,
+                            &patch_events,
+                            repo_dir_path,
+                        ))
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn find_latest_event(events:&Vec<Event>) -> Option<Event> {
+    let mut latest = match events.get(0) {
+        None => { return None },
+        Some(e) => e.clone(),
+    };
+    for e in events.iter() {
+        if e.created_at > latest.created_at {
+            latest = e.clone();
+        }
+    }
+    Some(latest)
+}
+
+fn get_merge_patch(
+    merge: &Event,
+    patch_events: &Vec<Event>,
+    repo_dir_path: &PathBuf,
+) -> Event{
+    let commit_id = tag_extract_value(
+        merge.tags.iter().find(|tag| tag_is_commit(tag))
+        .expect("merge event will have a commit tag")
+    );
+    // search in patch_events vector
+    match patch_events.iter().find(|p|
+        tag_extract_value(
+            p.tags.iter().find(|tag| tag_is_commit(tag))
+                .expect("patch event will have a commit tag")
+        ) == *commit_id
+    ) {
+        // found merge patch in patch_events
+        Some(patch) => patch.clone(),
+        None => {
+            let patch_path = repo_dir_path.join(format!(
+                ".ngit/patches/{}.json",
+                commit_id
+            ));
+            if patch_path.exists() {
+                // found merge patch in .ngit/patches
+                load_event(patch_path)
+                    .expect("patch at path that exists renders as event")
+            }
+            else {
+                panic!("cannot find patch from merge event in event vector or .ngit folder");
+            }
+        },
+    }
+}