import spaces
import jiwer
import numpy as np
import re
import gradio as gr

def split_into_sentences(text):
    """
    Simple sentence tokenizer using regular expressions.
    Splits text into sentences based on punctuation.
    """
    # Split text into sentences using regex
    sentences = re.split(r'(?<=[.!?])\s*', text)
    # Clean up empty strings and whitespace
    sentences = [s.strip() for s in sentences if s.strip()]
    return sentences

@spaces.GPU()
def calculate_wer(reference, hypothesis):
    """
    Calculate the Word Error Rate (WER) using jiwer.
    """
    wer = jiwer.wer(reference, hypothesis)
    return wer

@spaces.GPU()
def calculate_cer(reference, hypothesis):
    """
    Calculate the Character Error Rate (CER) using jiwer.
    """
    cer = jiwer.cer(reference, hypothesis)
    return cer

@spaces.GPU()
def calculate_sentence_wer(reference, hypothesis):
    """
    Calculate WER for each sentence and overall statistics.
    """
    try:
        reference_sentences = split_into_sentences(reference)
        hypothesis_sentences = split_into_sentences(hypothesis)

        if len(reference_sentences) != len(hypothesis_sentences):
            raise ValueError("Reference and hypothesis must contain the same number of sentences")

        sentence_wers = []
        for ref, hyp in zip(reference_sentences, hypothesis_sentences):
            sentence_wer = jiwer.wer(ref, hyp)
            sentence_wers.append(sentence_wer)

        if not sentence_wers:
            return {
                "sentence_wers": [],
                "average_wer": 0.0,
                "std_dev": 0.0
            }

        average_wer = np.mean(sentence_wers)
        std_dev = np.std(sentence_wers)

        return {
            "sentence_wers": sentence_wers,
            "average_wer": average_wer,
            "std_dev": std_dev
        }
    except Exception as e:
        raise e

@spaces.GPU()
def process_files(reference_file, hypothesis_file):
    try:
        with open(reference_file.name, 'r') as f:
            reference_text = f.read()

        with open(hypothesis_file.name, 'r') as f:
            hypothesis_text = f.read()

        wer_value = calculate_wer(reference_text, hypothesis_text)
        cer_value = calculate_cer(reference_text, hypothesis_text)
        sentence_wer_stats = calculate_sentence_wer(reference_text, hypothesis_text)

        return {
            "WER": wer_value,
            "CER": cer_value,
            "Sentence WERs": sentence_wer_stats["sentence_wers"],
            "Average WER": sentence_wer_stats["average_wer"],
            "Standard Deviation": sentence_wer_stats["std_dev"]
        }
    except Exception as e:
        return {"error": str(e)}

def format_sentence_wer_stats(sentence_wers, average_wer, std_dev):
    if not sentence_wers:
        return "All sentences match perfectly!"

    md = "### Sentence-level WER Analysis\n\n"
    md += f"* Average WER: {average_wer:.2f}\n"
    md += f"* Standard Deviation: {std_dev:.2f}\n\n"
    md += "### WER for Each Sentence\n\n"
    for i, wer in enumerate(sentence_wers):
        md += f"* Sentence {i+1}: {wer:.2f}\n"
    return md

def main():
    with gr.Blocks() as demo:
        gr.Markdown("# ASR Metrics Calculator")

        with gr.Row():
            reference_file = gr.File(label="Upload Reference File")
            hypothesis_file = gr.File(label="Upload Hypothesis File")

        with gr.Row():
            reference_preview = gr.Textbox(label="Reference Preview", lines=3)
            hypothesis_preview = gr.Textbox(label="Hypothesis Preview", lines=3)

        with gr.Row():
            compute_button = gr.Button("Compute Metrics")
            results_output = gr.JSON(label="Results")
            wer_stats_output = gr.Markdown(label="WER Statistics")

        # Update previews when files are uploaded
        def update_previews(ref_file, hyp_file):
            ref_text = ""
            hyp_text = ""

            if ref_file:
                with open(ref_file.name, 'r') as f:
                    ref_text = f.read()[:200]  # Show first 200 characters
            if hyp_file:
                with open(hyp_file.name, 'r') as f:
                    hyp_text = f.read()[:200]  # Show first 200 characters

            return ref_text, hyp_text

        reference_file.change(
            fn=update_previews,
            inputs=[reference_file, hypothesis_file],
            outputs=[reference_preview, hypothesis_preview]
        )
        hypothesis_file.change(
            fn=update_previews,
            inputs=[reference_file, hypothesis_file],
            outputs=[reference_preview, hypothesis_preview]
        )

        def process_and_display(ref_file, hyp_file):
            result = process_files(ref_file, hyp_file)
            if "error" in result:
                return {}, {}, "Error: " + result["error"]

            metrics = {
                "WER": result["WER"],
                "CER": result["CER"]
            }

            wer_stats_md = format_sentence_wer_stats(
                result["Sentence WERs"],
                result["Average WER"],
                result["Standard Deviation"]
            )

            return metrics, wer_stats_md

        compute_button.click(
            fn=process_and_display,
            inputs=[reference_file, hypothesis_file],
            outputs=[results_output, wer_stats_output]
        )

    demo.launch()

if __name__ == "__main__":
    main()