diff --git a/src/types/wrapper.ts b/src/types/wrapper.ts
new file mode 100644
index 0000000..faf74ec
--- /dev/null
+++ b/src/types/wrapper.ts
@@ -0,0 +1,138 @@
+import { journey_template, leg_template } from "./format"
+
+const date_day_diff = (d0: Date, d1: Date): number =>
+    (d1.getTime() - d0.getTime()) / (1000 * 60 * 60 * 24)
+
+class journey_wrapper {
+    id: string
+    data: journey = journey_template;
+    sel_leg: number = 0;
+    sel_day: number = 0;
+
+    constructor(id: string) {
+        this.id = id;
+    }
+
+    leg_first = () => this.data.main[0]
+    leg_last = () => this.data.main[this.leg_count() - 1]
+    leg_count(): number {
+        return this.data.main.length;
+    }
+    leg_len(idx: number = null): number {
+        let d = this.leg_get(idx == null ? this.sel_leg : idx).date_range;
+        return d ? date_day_diff(d[0], d[1]) + 1 : 1;
+    }
+    add_leg(): void {
+        if (this.data.main == undefined) this.data.main = [];
+        this.data.main.push(leg_template);
+    }
+    rm_leg(idx: number): void {
+        this.data.main.splice(idx, 1);
+        if (this.sel_leg == idx) this.leg_prev();
+    }
+    tot_len(): number | "?" {
+        if (this.leg_count() == 0) return 0;
+        try {
+            let d0 = this.leg_first().date_range[0]
+            let d1 = this.leg_last().date_range[1]
+            return date_day_diff(d0, d1);
+        } catch {
+            return "?";
+        }
+    }
+    leg_sel(idx: number): void {
+        this.sel_leg = idx;
+        this.sel_day = 1;
+    }
+    leg_get(idx: number = null): leg {
+        return this.data.main[idx == null ? this.sel_leg : idx]
+    }
+    leg_next(): void {
+        this.sel_leg = Math.min(this.sel_leg + 1, this.leg_count() - 1);
+        this.sel_day = 0;
+    }
+    leg_prev(): void {
+        this.sel_leg = Math.max(this.sel_leg - 1, 0);
+        this.sel_day = 0;
+    }
+    day_next() {
+        this.sel_day += 1
+        if (this.sel_day > this.leg_len() - 1) {
+            if (this.sel_leg < this.leg_count() - 1) {
+                this.leg_next()
+                this.sel_day = 0;
+            } else {
+                this.sel_day = this.leg_len() - 1;
+            }
+        }
+    }
+    day_prev() {
+        this.sel_day -= 1
+        if (this.sel_day < 0) {
+            if (this.sel_leg > 0) {
+                this.leg_prev()
+                this.sel_day = this.leg_len() - 1;
+            } else {
+                this.sel_day = 0;
+            }
+        }
+    }
+    date_sel(): string {
+        if (this.sel_day < 0) return "?";
+        if (!this.leg_get().date_range)
+            return "?";
+        var date = new Date(
+            this.leg_get().date_range[0],
+        );
+        date.setDate(date.getDate() + this.sel_day);
+        return date.toLocal();
+    }
+    date_tot() {
+        if (this.leg_count() == 0) return "";
+        try {
+            return `${this.leg_first().date_range[0].toLocal()} - ${this.leg_last().date_range[1].toLocal()}`;
+        } catch {
+            return "?";
+        }
+    }
+
+    date_update(idx: number) {
+        let date_range = this.leg_get(idx).date_range;
+        let start_end = [0, 0];
+        let step_len = 0;
+
+        let last_start = date_range[0];
+        for (let i = idx - 1; i >= 0; --i) {
+            step_len = this.leg_len(i) - 1;
+            if (this.leg_get(i).date_range) {
+                start_end = [last_start.getDate() - step_len, last_start.getDate()];
+            } else {
+                this.leg_get(i).date_range = [new Date(), new Date()];
+                start_end = [last_start.getDate() - step_len, last_start.getDate()];
+            }
+            this.leg_get(i).date_range[0].setTime(last_start.getTime());
+            this.leg_get(i).date_range[0].setDate(start_end[0]);
+            this.leg_get(i).date_range[1].setTime(last_start.getTime());
+            this.leg_get(i).date_range[1].setDate(start_end[1]);
+            last_start = this.leg_get(i).date_range[0];
+        }
+
+        let last_end = date_range[1];
+        for (let i = idx + 1; i < this.leg_count(); ++i) {
+            step_len = this.leg_len(i) - 1;
+            if (this.leg_get(i).date_range) {
+                start_end = [last_end.getDate(), last_end.getDate() + step_len];
+            } else {
+                this.leg_get(i).date_range = [new Date(), new Date()];
+                start_end = [last_end.getDate(), last_end.getDate() + step_len];
+            }
+            this.leg_get(i).date_range[0].setTime(last_end.getTime());
+            this.leg_get(i).date_range[0].setDate(start_end[0]);
+            this.leg_get(i).date_range[1].setTime(last_end.getTime());
+            this.leg_get(i).date_range[1].setDate(start_end[1]);
+            last_end = this.leg_get(i).date_range[1];
+        }
+    }
+}
+
+export default journey_wrapper;
\ No newline at end of file