// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
// TRANSPILATION TABLES
/**
 * Transpiles GLSL 3.00 shader source code to target GLSL version (3.00 or 1.00)
 *
 * @note We always run transpiler even if same version e.g. 3.00 => 3.00
 * @note For texture sampling transpilation, apps need to use non-standard texture* calls in GLSL 3.00 source
 * RFC: https://github.com/visgl/luma.gl/blob/7.0-release/dev-docs/RFCs/v6.0/portable-glsl-300-rfc.md
 */
export function transpileGLSLShader(source, stage) {
    const sourceGLSLVersion = Number(source.match(/^#version[ \t]+(\d+)/m)?.[1] || 100);
    if (sourceGLSLVersion !== 300) {
        // TODO - we splurge on a longer error message to help deck.gl custom layer developers
        throw new Error('luma.gl v9 only supports GLSL 3.00 shader sources');
    }
    switch (stage) {
        case 'vertex':
            source = convertShader(source, ES300_VERTEX_REPLACEMENTS);
            return source;
        case 'fragment':
            source = convertShader(source, ES300_FRAGMENT_REPLACEMENTS);
            return source;
        default:
            // Unknown shader stage
            throw new Error(stage);
    }
}
/** Simple regex replacements for GLSL ES 1.00 syntax that has changed in GLSL ES 3.00 */
const ES300_REPLACEMENTS = [
    // Fix poorly formatted version directive
    [/^(#version[ \t]+(100|300[ \t]+es))?[ \t]*\n/, '#version 300 es\n'],
    // The individual `texture...()` functions were replaced with `texture()` overloads
    [/\btexture(2D|2DProj|Cube)Lod(EXT)?\(/g, 'textureLod('],
    [/\btexture(2D|2DProj|Cube)(EXT)?\(/g, 'texture(']
];
const ES300_VERTEX_REPLACEMENTS = [
    ...ES300_REPLACEMENTS,
    // `attribute` keyword replaced with `in`
    [makeVariableTextRegExp('attribute'), 'in $1'],
    // `varying` keyword replaced with `out`
    [makeVariableTextRegExp('varying'), 'out $1']
];
/** Simple regex replacements for GLSL ES 1.00 syntax that has changed in GLSL ES 3.00 */
const ES300_FRAGMENT_REPLACEMENTS = [
    ...ES300_REPLACEMENTS,
    // `varying` keyword replaced with `in`
    [makeVariableTextRegExp('varying'), 'in $1']
];
function convertShader(source, replacements) {
    for (const [pattern, replacement] of replacements) {
        source = source.replace(pattern, replacement);
    }
    return source;
}
/**
 * Creates a regexp that tests for a specific variable type
 * @example
 *   should match:
 *     in float weight;
 *     out vec4 positions[2];
 *   should not match:
 *     void f(out float a, in float b) {}
 */
function makeVariableTextRegExp(qualifier) {
    return new RegExp(`\\b${qualifier}[ \\t]+(\\w+[ \\t]+\\w+(\\[\\w+\\])?;)`, 'g');
}