let basePath = ''

/** Sets the library's base path to the specified directory. */
export function setBasePath(path: string) {
    basePath = path
}

/**
 * Gets the library's base path.
 *
 * The base path is used to load assets such as icons and images, so it needs to be set for components to work properly.
 * By default, this script will look for a script ending in terra-ui-components.js or terra-ui-components-autoloader.js and set the base path
 * to the directory that contains that file. To override this behavior, you can add the data-terra-ui-components attribute to any
 * script on the page (it probably makes the most sense to attach it to the Terra script, but it could also be on a
 * bundle). The value can be a local folder or it can point to a CORS-enabled endpoint such as a CDN.
 *
 *   <script src="bundle.js" data-terra-ui-components="/custom/base/path"></script>
 *
 * Alternatively, you can set the base path manually using the exported setBasePath() function.
 *
 * @param subpath - An optional path to append to the base path.
 */
export function getBasePath(subpath = '') {
    if (!basePath) {
        const scripts = [
            ...document.getElementsByTagName('script'),
        ] as HTMLScriptElement[]
        const configScript = scripts.find(script =>
            script.hasAttribute('data-terra-ui-components')
        )

        if (configScript) {
            // Use the data-terra-ui-components attribute
            setBasePath(configScript.getAttribute('data-terra-ui-components')!)
        } else {
            const fallbackScript = scripts.find(s => {
                return (
                    /terra-ui-components(\.min)?\.js($|\?)/.test(s.src) ||
                    /terra-ui-components-autoloader(\.min)?\.js($|\?)/.test(s.src)
                )
            })
            let path = ''

            if (fallbackScript) {
                path = fallbackScript.getAttribute('src')!
            }

            setBasePath(path.split('/').slice(0, -1).join('/'))
        }
    }

    // Return the base path without a trailing slash. If one exists, append the subpath separated by a slash.
    return (
        basePath.replace(/\/$/, '') +
        (subpath ? `/${subpath.replace(/^\//, '')}` : ``)
    )
}
