Added an iCal parser

src/ical/parser.rs

@@ -0,0 +1,150 @@
+//! A module to parse ICal files
+
+use std::error::Error;
+
+use ical::parser::ical::component::{IcalCalendar, IcalEvent, IcalTodo};
+
+use crate::Item;
+use crate::item::SyncStatus;
+use crate::item::ItemId;
+use crate::Task;
+use crate::Event;
+
+
+/// Parse an iCal file into the internal representation [`crate::Item`]
+pub fn parse(content: &str, item_id: ItemId, sync_status: SyncStatus) -> Result<Item, Box<dyn Error>> {
+    let mut reader = ical::IcalParser::new(content.as_bytes());
+    let parsed_item = match reader.next() {
+        None => return Err(format!("Invalid uCal data to parse for item {}", item_id).into()),
+        Some(item) => match item {
+            Err(err) => return Err(format!("Unable to parse uCal data for item {}: {}", item_id, err).into()),
+            Ok(item) => item,
+        }
+    };
+
+    let item = match assert_single_type(&parsed_item)? {
+        CurrentType::Event(_) => {
+            Item::Event(Event::new())
+        },
+
+        CurrentType::Todo(todo) => {
+            let mut name = None;
+            for prop in &todo.properties {
+                if prop.name == "SUMMARY" {
+                    name = prop.value.clone();
+                    break;
+                }
+            }
+            let name = match name {
+                Some(name) => name,
+                None => return Err(format!("Missing name for item {}", item_id).into()),
+            };
+
+            Item::Task(Task::new(name, item_id, sync_status))
+        },
+    };
+
+
+    // What to do with multiple items?
+    if reader.next().map(|r| r.is_ok()) == Some(true) {
+        return Err("Parsing multiple items are not supported".into());
+    }
+
+    Ok(item)
+}
+
+enum CurrentType<'a> {
+    Event(&'a IcalEvent),
+    Todo(&'a IcalTodo),
+}
+
+fn assert_single_type<'a>(item: &'a IcalCalendar) -> Result<CurrentType<'a>, Box<dyn Error>> {
+    let n_events = item.events.len();
+    let n_todos = item.todos.len();
+    let n_journals = item.journals.len();
+
+    if n_events == 1 {
+        if n_todos != 0 || n_journals != 0 {
+            return Err("Only a single TODO or a single EVENT is supported".into());
+        } else {
+            return Ok(CurrentType::Event(&item.events[0]));
+        }
+    }
+
+    if n_todos == 1 {
+        if n_events != 0 || n_journals != 0 {
+            return Err("Only a single TODO or a single EVENT is supported".into());
+        } else {
+            return Ok(CurrentType::Todo(&item.todos[0]));
+        }
+    }
+
+    return Err("Only a single TODO or a single EVENT is supported".into());
+}
+
+
+#[cfg(test)]
+mod test {
+    const EXAMPLE_ICAL: &str = r#"BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Nextcloud Tasks v0.13.6
+BEGIN:VTODO
+UID:0633de27-8c32-42be-bcb8-63bc879c6185
+CREATED:20210321T001600
+LAST-MODIFIED:20210321T001600
+DTSTAMP:20210321T001600
+SUMMARY:Do not forget to do this
+END:VTODO
+END:VCALENDAR
+"#;
+
+    const EXAMPLE_MULTIPLE_ICAL: &str = r#"BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Nextcloud Tasks v0.13.6
+BEGIN:VTODO
+UID:0633de27-8c32-42be-bcb8-63bc879c6185
+CREATED:20210321T001600
+LAST-MODIFIED:20210321T001600
+DTSTAMP:20210321T001600
+SUMMARY:Call Mom
+END:VTODO
+END:VCALENDAR
+BEGIN:VCALENDAR
+BEGIN:VTODO
+UID:0633de27-8c32-42be-bcb8-63bc879c6185
+CREATED:20210321T001600
+LAST-MODIFIED:20210321T001600
+DTSTAMP:20210321T001600
+SUMMARY:Buy a gift for Mom
+END:VTODO
+END:VCALENDAR
+"#;
+
+    use super::*;
+    use crate::item::VersionTag;
+
+    #[test]
+    fn test_ical_parsing() {
+        let version_tag = VersionTag::from(String::from("test-tag"));
+        let sync_status = SyncStatus::Synced(version_tag);
+        let item_id: ItemId = "http://some.id/for/testing".parse().unwrap();
+
+        let item = parse(EXAMPLE_ICAL, item_id.clone(), sync_status.clone()).unwrap();
+        let task = item.unwrap_task();
+
+        assert_eq!(task.name(), "Do not forget to do this");
+        assert_eq!(task.id(), &item_id);
+        assert_eq!(task.completed(), false);
+        assert_eq!(task.sync_status(), &sync_status);
+    }
+
+    #[test]
+    fn test_multiple_items_in_ical() {
+        let version_tag = VersionTag::from(String::from("test-tag"));
+        let sync_status = SyncStatus::Synced(version_tag);
+        let item_id: ItemId = "http://some.id/for/testing".parse().unwrap();
+
+        let item = parse(EXAMPLE_MULTIPLE_ICAL, item_id.clone(), sync_status.clone());
+        assert!(item.is_err());
+    }
+}