feat(performance): removed double memory usage when reading/writing text files

[RohitKushvaha01]

No description provided.

[greptile-apps]

Greptile Summary

This PR eliminates the base64 encode/decode round-trip that previously doubled memory usage when reading and writing text files on external storage. Two new native paths (readAsText / writeText) allow the Java layer to handle charset conversion directly, avoiding an intermediate ArrayBuffer allocation and transfer across the Cordova bridge.

• Read path: readFile(encoding) now calls the new Java readAsText method which uses InputStreamReader to decode directly to a String; BOM stripping (U+FEFF) is applied in JavaScript before returning or parsing JSON.
• Write path: writeFile(content, encoding) for string content now calls writeText, which encodes the string to bytes in Java with the resolved charset and writes via a try-with-resources OutputStream.
• getEncodingName: Common charset-resolution logic is extracted from decode/encode into a shared helper, reducing duplication.

Confidence Score: 5/5

Safe to merge; the new native text paths behave correctly for all standard encodings.

The read and write paths correctly handle charset resolution, BOM stripping, and JSON parsing. The writeText OutputStream is properly managed in a try-with-resources block. The only note is in readAsText where the InputStream is opened just before its try-with-resources wrapper — closing cascades correctly on all normal paths, making this only a concern under very unlikely allocation failures.

The readAsText method in SDcard.java could tighten its resource management by declaring the InputStream inside its own try-with-resources arm.

Important Files Changed

Filename	Overview
src/fileSystem/externalFs.js	Adds readAsText and writeText wrappers that bypass the base64 encode/decode round-trip; readFile now dispatches directly to text-based paths when an encoding is given, and BOM stripping is correctly applied in JS before returning the text.
src/plugins/sdcard/src/android/SDcard.java	Adds readAsText and writeText Java methods; writeText correctly uses try-with-resources for the OutputStream, but readAsText opens the InputStream outside the TWR block, creating a minor resource leak path on unlikely allocation failures.
src/plugins/sdcard/www/plugin.js	Adds readAsText and writeText Cordova bridge methods with correct argument ordering matching the Java dispatch.
src/utils/encodings.js	Extracts shared charset-resolution logic into getEncodingName, refactoring decode and encode to use it — clean deduplication with no behavioural change.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant JS as JavaScript (externalFs.js)
    participant Bridge as Cordova Bridge
    participant Java as SDcard.java

    Note over JS,Java: OLD read path (double memory)
    JS->>Bridge: sdcard.read(url) to ArrayBuffer via base64
    Bridge->>Java: read action
    Java-->>Bridge: byte[] as base64 String
    Bridge-->>JS: ArrayBuffer
    JS->>JS: decode(buffer, charset) to String 2x memory

    Note over JS,Java: NEW read path (single pass)
    JS->>Bridge: sdcard.readAsText(url, charset)
    Bridge->>Java: readAsText action
    Java->>Java: InputStreamReader(is, charset) to String
    Java-->>Bridge: String
    Bridge-->>JS: String
    JS->>JS: BOM strip then return text

    Note over JS,Java: NEW write path (single pass)
    JS->>Bridge: sdcard.writeText(url, text, charset)
    Bridge->>Java: writeText action
    Java->>Java: content.getBytes(charset) then write to disk

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sequenceDiagram
    participant JS as JavaScript (externalFs.js)
    participant Bridge as Cordova Bridge
    participant Java as SDcard.java

    Note over JS,Java: OLD read path (double memory)
    JS->>Bridge: sdcard.read(url) to ArrayBuffer via base64
    Bridge->>Java: read action
    Java-->>Bridge: byte[] as base64 String
    Bridge-->>JS: ArrayBuffer
    JS->>JS: decode(buffer, charset) to String 2x memory

    Note over JS,Java: NEW read path (single pass)
    JS->>Bridge: sdcard.readAsText(url, charset)
    Bridge->>Java: readAsText action
    Java->>Java: InputStreamReader(is, charset) to String
    Java-->>Bridge: String
    Bridge-->>JS: String
    JS->>JS: BOM strip then return text

    Note over JS,Java: NEW write path (single pass)
    JS->>Bridge: sdcard.writeText(url, text, charset)
    Bridge->>Java: writeText action
    Java->>Java: content.getBytes(charset) then write to disk

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