1 files changed, 65 insertions, 0 deletions
diff --git a/src/state.ts b/src/state.ts
new file mode 100644
index 0000000..634319a
--- /dev/null
+++ b/src/state.ts
@@ -0,0 +1,65 @@
+import * as Serialization from 'serialization'
+
+const L = window.L
+
+// State
+
+var nextIndex: Index = 0
+
+export type State = Marker[]
+export type Index = number
+
+var state: State = []
+
+export interface Marker {
+  pos: L.Pos,
+  name: string,
+  color: string,
+  icon: string,
+  radius: number,
+}
+
+export function reset(s: State) {
+  state = s
+  nextIndex = s.length
+}
+
+// CRUD
+
+export function add(marker: Marker): Index {
+  const index = nextIndex
+  state[index] = marker
+  nextIndex += 1
+  pushState()
+  return index
+}
+
+export function update(index: Index, marker: Marker) {
+  state[index] = marker
+  pushState()
+}
+
+export function remove(index: Index) {
+  delete state[index]
+  pushState()
+}
+
+// History
+
+function pushState() {
+  const encoded = Serialization.encode(Object.values(state))
+  history.pushState('', '', `#${encoded}`)
+}
+
+// Inspection
+
+export function colors() {
+  return [...new Set(Object.values(state).map(({ color }) => color))]
+}
+
+export function last(): Marker | undefined {
+  const nonempty = Object.values(state)
+  return nonempty.length > 0
+    ? nonempty.slice(-1)[0]
+    : undefined
+}