// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
import { glsl } from "./highlight.js";
const FS_GLES = `\
out vec4 transform_output;
void main() {
transform_output = vec4(0);
}`;
const FS300 = `#version 300 es\n${FS_GLES}`;
// Prase given glsl line and return qualifier details or null
export function getQualifierDetails(line, qualifiers) {
    qualifiers = Array.isArray(qualifiers) ? qualifiers : [qualifiers];
    const words = line.replace(/^\s+/, '').split(/\s+/);
    // TODO add support for precession qualifiers (highp, mediump and lowp)
    const [qualifier, type, definition] = words;
    if (!qualifiers.includes(qualifier) || !type || !definition) {
        return null;
    }
    const name = definition.split(';')[0];
    return { qualifier, type, name };
}
/**
 * Given the shader input and output variable names,
 * builds and return a pass through fragment shader.
 */
export function getPassthroughFS(options) {
    const { input, inputChannels, output } = options || {};
    if (!input) {
        // Default shader
        return FS300;
    }
    if (!inputChannels) {
        throw new Error('inputChannels');
    }
    const inputType = channelCountToType(inputChannels);
    const outputValue = convertToVec4(input, inputChannels);
    return `\
#version 300 es
in ${inputType} ${input};
out vec4 ${output};
void main() {
  ${output} = ${outputValue};
}`;
}
/** convert glsl type to suffix */
export function typeToChannelSuffix(type) {
    // prettier-ignore
    switch (type) {
        case 'float': return 'x';
        case 'vec2': return 'xy';
        case 'vec3': return 'xyz';
        case 'vec4': return 'xyzw';
        default:
            throw new Error(type);
    }
}
/** convert glsl type to channel count */
export function typeToChannelCount(type) {
    // prettier-ignore
    switch (type) {
        case 'float': return 1;
        case 'vec2': return 2;
        case 'vec3': return 3;
        case 'vec4': return 4;
        default:
            throw new Error(type);
    }
}
function channelCountToType(channels) {
    // prettier-ignore
    switch (channels) {
        case 1: return 'float';
        case 2: return 'vec2';
        case 3: return 'vec3';
        case 4: return 'vec4';
        default:
            throw new Error(`invalid channels: ${channels}`);
    }
}
/** Returns glsl instruction for converting to vec4 */
export function convertToVec4(variable, channels) {
    // prettier-ignore
    switch (channels) {
        case 1: return `vec4(${variable}, 0.0, 0.0, 1.0)`;
        case 2: return `vec4(${variable}, 0.0, 1.0)`;
        case 3: return `vec4(${variable}, 1.0)`;
        case 4: return variable;
        default:
            throw new Error(`invalid channels: ${channels}`);
    }
}