feat(select): improve option navigation by key (#856)

This PR allows users to easily access target option based on their
keyboard input.

Closes [#686](#686)

src/components/select/bl-select.stories.mdx

@@ -146,6 +146,7 @@ ${SelectTemplate(args)}
 # Select
 
 <bl-badge icon="document">[ADR](https://github.com/Trendyol/baklava/issues/88)</bl-badge>
+<bl-badge icon="document">[Accessibility](https://github.com/Trendyol/baklava/issues/686#issuecomment-2079522703)</bl-badge>
 <bl-badge icon="puzzle">[Figma](https://www.figma.com/file/RrcLH0mWpIUy4vwuTlDeKN/Baklava-Design-Guide?node-id=25%3A3606)</bl-badge>
 
 Select component is a component for selecting a value from a list of options.

src/components/select/bl-select.test.ts

@@ -632,6 +632,8 @@ describe("bl-select", () => {
           <bl-select-option value="basketball">Basketball</bl-select-option>
           <bl-select-option value="football">Football</bl-select-option>
           <bl-select-option value="tennis">Tennis</bl-select-option>
+          <bl-select-option value="boxing">Boxing</bl-select-option>
+          <bl-select-option value="hockey" disabled>Hockey</bl-select-option>
         </bl-select>
         <input id="nextinput" />
       </div>`);
@@ -758,6 +760,105 @@ describe("bl-select", () => {
       //then
       expect((document.activeElement as BlSelectOption).value).to.equal(firstOption?.value);
     });
+
+    it("should focus the first matching option when typing a single character", async () => {
+      const firstOption = el.querySelector<BlSelectOption>("bl-select-option");
+
+       //given
+       await sendKeys({
+         press: tabKey,
+       });
+       await sendKeys({
+        press: "Space",
+      });
+       await sendKeys({
+         press: "b",
+       }); 
+
+       //then
+       expect((document.activeElement as BlSelectOption).value).to.equal(firstOption?.value);
+    });
+
+    it("should focus the first matching option when typing a single character with uppercase", async () => {
+      const firstOption = el.querySelector<BlSelectOption>("bl-select-option");
+
+       //given
+       await sendKeys({
+         press: tabKey,
+       });
+       await sendKeys({
+        press: "Space",
+      });
+       await sendKeys({
+         press: "B",
+       }); 
+
+       //then
+       expect((document.activeElement as BlSelectOption).value).to.equal(firstOption?.value);
+    });
+
+    it("should focus the first matching option when typing two characters", async () => {
+      const fourthOption = el.querySelector<BlSelectOption>("bl-select-option:nth-child(4)");
+
+       //given
+       await sendKeys({
+         press: tabKey,
+       });
+       await sendKeys({
+        press: "Space",
+      });
+       await sendKeys({
+         press: "b",
+       }); 
+       await sendKeys({
+        press: "o",
+      }); 
+
+       //then
+       expect((document.activeElement as BlSelectOption).value).to.equal(fourthOption?.value);
+    });
+
+    it("should reset typed characters after an interval of inactivity", async () => {
+      const secondOption = el.querySelector<BlSelectOption>("bl-select-option:nth-child(2)");
+
+      // when
+      await sendKeys({
+        press: tabKey,
+      });
+      await sendKeys({
+        press: "Space",
+      });
+      await sendKeys({
+        press: "b",
+      });
+      // Wait for an interval of inactivity
+      await new Promise(resolve => setTimeout(resolve, 600));
+
+      await sendKeys({
+        press: "f",
+      });
+
+      //then
+      expect((document.activeElement as BlSelectOption).value).to.equal(secondOption?.value);
+    });
+
+    it("should not focus on the disabled option even if it matches the typed character", async () => {
+      const focusedOptions = el.querySelectorAll("bl-select-option:focus");
+
+       //given
+       await sendKeys({
+         press: tabKey,
+       });
+       await sendKeys({
+        press: "Space",
+      });
+       await sendKeys({
+         press: "h",
+       }); 
+
+       //then
+       expect(focusedOptions.length).to.equal(0);
+    });
   });
 
   describe("select all", () => {

src/components/select/bl-select.ts

@@ -571,6 +571,35 @@ export default class BlSelect<ValueType extends FormValue = string> extends Form
   }
 
   private focusedOptionIndex = -1;
+  private lastKeyPressedTime = 0;
+  private typedCharacters = "";
+  private keyPressThreshold = 500;
+
+  private handleFocusOptionByKey(key: string) {
+    const currentTime = Date.now();
+    const elapsedTimeSinceLastKeyPress = currentTime - this.lastKeyPressedTime;
+
+    if (elapsedTimeSinceLastKeyPress > this.keyPressThreshold) {
+      this.typedCharacters = "";
+    }
+
+    this.lastKeyPressedTime = currentTime;
+    this.typedCharacters += key.toLowerCase();
+
+    const matchingOptionIndex = this.options.findIndex(option => {
+      if (option.disabled) {
+        return false;
+      }
+      const optionText = option.innerText.trim().toLowerCase();
+
+      return optionText.startsWith(this.typedCharacters);
+    });
+
+    if (matchingOptionIndex !== -1) {
+      this.focusedOptionIndex = matchingOptionIndex;
+      this.options[matchingOptionIndex].focus();
+    }
+  }
 
   private handleKeydown(event: KeyboardEvent) {
     if (this.focusedOptionIndex === -1 && ["Enter", "Space"].includes(event.code)) {
@@ -595,6 +624,8 @@ export default class BlSelect<ValueType extends FormValue = string> extends Form
       this.options[this.focusedOptionIndex].focus();
 
       event.preventDefault();
+    } else if (this._isPopoverOpen && !this.searchBar) {
+      this.handleFocusOptionByKey(event.key);
     }
   }