1 files changed, 74 insertions, 0 deletions
diff --git a/src/step.ts b/src/step.ts
new file mode 100644
index 0000000..13ca183
--- /dev/null
+++ b/src/step.ts
@@ -0,0 +1,74 @@
+import * as Config from 'config'
+
+export type Step
+  = { name: 'warmup', remaining: number }
+  | { name: 'prepare', tabata: string, remaining: number }
+  | { name: 'work', tabata: string, cycle: number, remaining: number }
+  | { name: 'rest', tabata: string, cycle: number, remaining: number }
+  | { name: 'end' }
+
+export function prettyPrint(step: Step): string {
+  switch (step.name) {
+    case 'warmup':
+      return 'Warm Up'
+    case 'prepare':
+      return `${step.tabata}\nPreparation`
+    case 'work':
+      return `${step.tabata}\nWork ${step.cycle}`
+    case 'rest':
+      return `${step.tabata}\nRest ${step.cycle}`
+    case 'end':
+      return 'End!'
+  }
+}
+
+export function getAt(config: Config.Config, elapsed: number): Step {
+  if (elapsed < config.warmup) {
+    return {
+      name: 'warmup',
+      remaining: config.warmup - elapsed
+    }
+  }
+
+  const tabataElapsed = elapsed - config.warmup
+
+  const cycleDuration = config.work + config.rest
+  const tabataDuration = config.prepare + (config.cycles * cycleDuration)
+
+  if (tabataElapsed >= tabataDuration * config.tabatas.length) {
+    return { name: 'end' }
+  }
+
+  const tabata = config.tabatas[Math.floor(tabataElapsed / tabataDuration)]
+  const currentTabataElapsed = tabataElapsed % tabataDuration
+
+  if (currentTabataElapsed < config.prepare) {
+    return {
+      name: 'prepare',
+      tabata,
+      remaining: config.prepare - currentTabataElapsed
+    }
+  } else {
+    const currentCycleElapsed = (currentTabataElapsed - config.prepare) % cycleDuration
+    const cycle =
+      currentTabataElapsed < config.prepare
+        ? 1
+        : Math.floor((currentTabataElapsed - config.prepare) / cycleDuration) + 1
+
+    if (currentCycleElapsed < config.work) {
+      return {
+        name: 'work',
+        tabata,
+        cycle,
+        remaining: config.work - currentCycleElapsed
+      }
+    } else {
+      return {
+        name: 'rest',
+        tabata,
+        cycle,
+        remaining: config.work + config.rest - currentCycleElapsed
+      }
+    }
+  }
+}