New navigation model (#1)

* Flatten all routing into a single stack

* Replace router with custom implementation

* Add shell header and titles

* Add tab selector

* Add back/forward history menus on longpress

* Fix: don't modify state during render

* Add refresh() to navigation and reroute navigations to the current location to refresh instead of add to history

* Cache screens during navigation to maintain scroll position and improve load-time for renders

1 files changed, 251 insertions, 0 deletions

diff --git a/src/state/models/navigation.ts b/src/state/models/navigation.ts
new file mode 100644
index 000000000..d5338ac05
--- /dev/null
+++ b/src/state/models/navigation.ts
@@ -0,0 +1,251 @@
+import {makeAutoObservable} from 'mobx'
+import {isObj, hasProp} from '../lib/type-guards'
+
+let __tabId = 0
+function genTabId() {
+  return ++__tabId
+}
+
+interface HistoryItem {
+  url: string
+  ts: number
+  title?: string
+}
+
+export class NavigationTabModel {
+  id = genTabId()
+  history: HistoryItem[] = [{url: '/', ts: Date.now()}]
+  index = 0
+
+  constructor() {
+    makeAutoObservable(this, {
+      serialize: false,
+      hydrate: false,
+    })
+  }
+
+  // accessors
+  // =
+
+  get current() {
+    return this.history[this.index]
+  }
+
+  get canGoBack() {
+    return this.index > 0
+  }
+
+  get canGoForward() {
+    return this.index < this.history.length - 1
+  }
+
+  getBackList(n: number) {
+    const start = Math.max(this.index - n, 0)
+    const end = Math.min(this.index, n)
+    return this.history.slice(start, end).map((item, i) => ({
+      url: item.url,
+      title: item.title,
+      index: start + i,
+    }))
+  }
+
+  get backTen() {
+    return this.getBackList(10)
+  }
+
+  getForwardList(n: number) {
+    const start = Math.min(this.index + 1, this.history.length)
+    const end = Math.min(this.index + n, this.history.length)
+    return this.history.slice(start, end).map((item, i) => ({
+      url: item.url,
+      title: item.title,
+      index: start + i,
+    }))
+  }
+
+  get forwardTen() {
+    return this.getForwardList(10)
+  }
+
+  // navigation
+  // =
+
+  navigate(url: string, title?: string) {
+    if (this.current?.url === url) {
+      this.refresh()
+    } else {
+      if (this.index < this.history.length - 1) {
+        this.history.length = this.index + 1
+      }
+      this.history.push({url, title, ts: Date.now()})
+      this.index = this.history.length - 1
+    }
+  }
+
+  refresh() {
+    this.history = [
+      ...this.history.slice(0, this.index),
+      {url: this.current.url, title: this.current.title, ts: Date.now()},
+      ...this.history.slice(this.index + 1),
+    ]
+  }
+
+  goBack() {
+    if (this.canGoBack) {
+      this.index--
+    }
+  }
+
+  goForward() {
+    if (this.canGoForward) {
+      this.index++
+    }
+  }
+
+  goToIndex(index: number) {
+    if (index >= 0 && index <= this.history.length - 1) {
+      this.index = index
+    }
+  }
+
+  setTitle(title: string) {
+    this.current.title = title
+  }
+
+  // persistence
+  // =
+
+  serialize(): unknown {
+    return {
+      history: this.history,
+      index: this.index,
+    }
+  }
+
+  hydrate(v: unknown) {
+    this.history = []
+    this.index = 0
+    if (isObj(v)) {
+      if (hasProp(v, 'history') && Array.isArray(v.history)) {
+        for (const item of v.history) {
+          if (
+            isObj(item) &&
+            hasProp(item, 'url') &&
+            typeof item.url === 'string'
+          ) {
+            let copy: HistoryItem = {
+              url: item.url,
+              ts:
+                hasProp(item, 'ts') && typeof item.ts === 'number'
+                  ? item.ts
+                  : Date.now(),
+            }
+            if (hasProp(item, 'title') && typeof item.title === 'string') {
+              copy.title = item.title
+            }
+            this.history.push(copy)
+          }
+        }
+      }
+      if (hasProp(v, 'index') && typeof v.index === 'number') {
+        this.index = v.index
+      }
+      if (this.index >= this.history.length - 1) {
+        this.index = this.history.length - 1
+      }
+    }
+  }
+}
+
+export class NavigationModel {
+  tabs: NavigationTabModel[] = [new NavigationTabModel()]
+  tabIndex = 0
+
+  constructor() {
+    makeAutoObservable(this, {
+      serialize: false,
+      hydrate: false,
+    })
+  }
+
+  // accessors
+  // =
+
+  get tab() {
+    return this.tabs[this.tabIndex]
+  }
+
+  isCurrentScreen(tabId: number, index: number) {
+    return this.tab.id === tabId && this.tab.index === index
+  }
+
+  // navigation
+  // =
+
+  navigate(url: string, title?: string) {
+    this.tab.navigate(url, title)
+  }
+
+  refresh() {
+    this.tab.refresh()
+  }
+
+  setTitle(title: string) {
+    this.tab.setTitle(title)
+  }
+
+  // tab management
+  // =
+
+  newTab(url: string, title?: string) {
+    const tab = new NavigationTabModel()
+    tab.navigate(url, title)
+    this.tabs.push(tab)
+    this.tabIndex = this.tabs.length - 1
+  }
+
+  setActiveTab(tabIndex: number) {
+    this.tabIndex = Math.max(Math.min(tabIndex, this.tabs.length - 1), 0)
+  }
+
+  closeTab(tabIndex: number) {
+    this.tabs = [
+      ...this.tabs.slice(0, tabIndex),
+      ...this.tabs.slice(tabIndex + 1),
+    ]
+    if (this.tabs.length === 0) {
+      this.newTab('/')
+    } else if (this.tabIndex >= this.tabs.length) {
+      this.tabIndex = this.tabs.length - 1
+    }
+  }
+
+  // persistence
+  // =
+
+  serialize(): unknown {
+    return {
+      tabs: this.tabs.map(t => t.serialize()),
+      tabIndex: this.tabIndex,
+    }
+  }
+
+  hydrate(v: unknown) {
+    this.tabs.length = 0
+    this.tabIndex = 0
+    if (isObj(v)) {
+      if (hasProp(v, 'tabs') && Array.isArray(v.tabs)) {
+        for (const tab of v.tabs) {
+          const copy = new NavigationTabModel()
+          copy.hydrate(tab)
+          if (copy.history.length) {
+            this.tabs.push(copy)
+          }
+        }
+      }
+      if (hasProp(v, 'tabIndex') && typeof v.tabIndex === 'number') {
+        this.tabIndex = v.tabIndex
+      }
+    }
+  }
+}