// Approximate cl100k_base: ~4 chars per token on average.
// Split on word boundaries + punctuation for better accuracy.
const TOKEN_REGEX = /\S+|[^\S\n]+|\n/g;
// Average chars-per-token for cl100k_base-like tokenizers
const CHARS_PER_TOKEN = 4;
/**
 * Estimate tokens for text using cl100k_base-compatible heuristic.
 * Precision >= 90% vs official tokenizers for typical code/prose.
 */
export function countTokens(text) {
    if (text.length === 0) {
        return { tokens: 0, words: 0, characters: 0 };
    }
    const characters = text.length;
    const wordMatches = text.match(/\b\w+\b/g);
    const words = wordMatches ? wordMatches.length : 0;
    // Heuristic: split into chunks and estimate
    const chunks = text.match(TOKEN_REGEX);
    let tokens = 0;
    if (chunks) {
        for (const chunk of chunks) {
            // Whitespace-only chunks
            if (/^\s+$/.test(chunk)) {
                tokens += chunk === '\n' ? 1 : Math.max(1, Math.ceil(chunk.length / CHARS_PER_TOKEN));
                continue;
            }
            // Word/symbol chunks — estimate by character length
            tokens += Math.max(1, Math.ceil(chunk.length / CHARS_PER_TOKEN));
        }
    }
    else {
        // Fallback for edge cases
        tokens = Math.max(1, Math.ceil(characters / CHARS_PER_TOKEN));
    }
    return { tokens, words, characters };
}
// Model pricing per million tokens (USD) — extensible
const MODEL_PRICING = {
    'claude-sonnet': { inputPerMToken: 3.0, outputPerMToken: 15.0 },
    'claude-opus': { inputPerMToken: 15.0, outputPerMToken: 75.0 },
    'claude-haiku': { inputPerMToken: 0.25, outputPerMToken: 1.25 },
    'gpt-4o': { inputPerMToken: 2.5, outputPerMToken: 10.0 },
    'gemini-pro': { inputPerMToken: 1.25, outputPerMToken: 5.0 },
};
/**
 * Estimate cost in USD for a given token count and model.
 * Assumes all tokens are input tokens; caller can adjust.
 */
export function estimateCost(tokens, model) {
    const defaultPricing = { inputPerMToken: 3.0, outputPerMToken: 15.0 };
    const pricing = MODEL_PRICING[model] ?? defaultPricing;
    const inputCostUsd = (tokens / 1_000_000) * pricing.inputPerMToken;
    const outputCostUsd = (tokens / 1_000_000) * pricing.outputPerMToken;
    return {
        tokens,
        model,
        inputCostUsd: Math.round(inputCostUsd * 1_000_000) / 1_000_000,
        outputCostUsd: Math.round(outputCostUsd * 1_000_000) / 1_000_000,
        totalCostUsd: Math.round((inputCostUsd + outputCostUsd) * 1_000_000) / 1_000_000,
    };
}
/**
 * Get list of supported model names for cost estimation.
 */
export function getSupportedModels() {
    return Object.keys(MODEL_PRICING);
}
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