// ==UserScript==
// @name         Wikipedia Language Redirector (Using Mediawiki API)
// @version      v3
// @match        https://en.wikipedia.org/wiki/*
// @description  Redirects wikipedia pages to alternate language pages in order of predefined preference
// @author       wheresmysurplusvalue
// @run-at       document-start
// @license      AGPL 3+
// ==/UserScript==

const LanguageList = ['no', 'nn', 'da', 'sv', 'eo', 'tok', 'ru', 'ja', 'zh'];

function main() {
    if (LanguageList.length == 0) {
        return;
    }

    const path = window.location.pathname;
    const title = parseTitle(path);

    if (title) {
        resolveTitle(title)
        .then(getLanguages)
        .then(chooseLanguage)
        .then(redirectLanguage)
        .catch(err => console.error(err));
    } else {
        console.log("Article title could not be parsed:", path);
    }
}

function redirectLanguage(pageLanguage) {
    window.location.href = `https://${pageLanguage.code}.wikipedia.org/wiki/${pageLanguage.key}`;
}

function chooseLanguage(availableLanguages) {
    const pageLanguage = filterLanguages(availableLanguages).next().value;
    if (!pageLanguage) {
        throw new Error(`Article not available in preferred languages: ${LanguageList}`);
    }
    return pageLanguage;
}

function* filterLanguages(availableLanguages) {
   for (const langCode of LanguageList) {
      for (const pageLanguage of availableLanguages) {
         if (pageLanguage.code == langCode) {
             yield pageLanguage;
         }
      }
   }
}

function parseTitle(path) {
    const regex = /^\/wiki\/(.*)/;
    const match = path.match(regex);

    if (!match) {
        console.error(`Could not parse title from path: ${path}`);
        return null;
    }

    const title = match[1];
    console.log("Extracted article title:", title);
    return title;
}

async function request(url) {
    const response = await fetch(url);
    if (!response.ok) {
        throw new Error(`HTTP error! url: ${url}, status: ${response.status}`);
    }
    return await response.json();
}

async function resolveTitle(title) {
    return getPage(title).then(data => data.key);
}

async function getPage(title) {
    const url = `/w/rest.php/v1/page/${title}/bare`;
    return requestPage(url, true);
}

async function requestPage(url, followRedirect) {
    return request(url).then(data => {
        console.log("data:", data);
        if (followRedirect && data.redirect_target) {
            return requestPage(data.redirect_target, followRedirect);
        }
        return data;
    });
}

async function getLanguages(title) {
    const url = `/w/rest.php/v1/page/${title}/links/language`;
    return request(url);
}

main();

// ==UserScript==
// @name         Wikipedia Language Redirector (Using Mediawiki API)
// @version      v2
// @match        https://en.wikipedia.org/wiki/*
// @description  Redirects wikipedia pages to alternate language pages in order of predefined preference
// @author       wheresmysurplusvalue
// @run-at       document-start
// @license      AGPL 3+
// ==/UserScript==

const LanguageList = ['nb', 'nn', 'da', 'sv', 'eo', 'tok', 'ru', 'ja', 'zh'];

function main() {
    const path = window.location.pathname;
    const title = getTitle(path);

    if (title) {
        getRealTitle(title)
        .then(title => getLanguages(title))
        .then(data => chooseLanguage(data));
    } else {
        console.log("Article title could not be parsed: ", path);
    }
}

function chooseLanguage(availableLanguages) {
   for (const langCode of LanguageList) {
      for (const pageLanguage of availableLanguages) {
         if (pageLanguage.code == langCode) {
             console.log("Found match: ", langCode);
             window.location.href = `https://${pageLanguage.code}.wikipedia.org/wiki/${pageLanguage.key}`;
             return;
         }
      }
   }
   console.log("Article not available in preferred languages.");
}

function getTitle(path) {
    const regex = /^\/wiki\/(.*)/;

    const match = path.match(regex);

    if (match) {
        const title = match[1];
        console.log("Extracted article title: ", title);

        return title;
    }

    return null;
}

async function request(url) {
    try {
        const response = await fetch(url);
        if (!response.ok) {
            throw new Error(`HTTP error! status: ${response.status}`);
        }
        const data = await response.json();
        return data;
    } catch (error) {
        console.error('Error fetching data:', error);
    }
}

async function getLanguages(title) {
    const url = `/w/rest.php/v1/page/${title}/links/language`;
    return request(url);
}

async function getRealTitle(title) {
    const url = `/w/rest.php/v1/page/${title}/bare`;
    return getPage(url).then(data => {
        console.log("Resolved title: ", data.key);
        return data.key;
    });
}

async function getPage(url) {
    return request(url).then(data => {
        console.log("data: ", data);
        if (data.redirect_target) {
            return getPage(data.redirect_target);
        }
        return data;
    });

}

main();

// ==UserScript==
// @name         Wikipedia Language Redirector (Using Mediawiki API)
// @version      v1
// @match        https://en.wikipedia.org/wiki/*
// @description  Redirects wikipedia pages to alternate language pages in order of predefined preference
// @author       wheresmysurplusvalue
// @run-at       document-start
// @license      AGPL 3+
// ==/UserScript==

const LanguageList = ['nb', 'nn', 'da', 'sv', 'eo', 'tok', 'ru', 'ja', 'zh'];

function handleResponse(json) {
   for (const langCode of LanguageList) {
      for (const pageLanguage of json) {
         if (pageLanguage.code == langCode) {
             console.log("Found match: ", langCode);
             window.location.href = `https://${pageLanguage.code}.wikipedia.org/wiki/${pageLanguage.key}`;
             return;
         }
      }
   }
   console.log("Article not available in preferred languages.");
}

const path = window.location.pathname;
const title = getTitle(path);

if (title) {
    getLanguages(title, handleResponse);
} else {
    console.log("Article title could not be parsed: ", path);
}

function getTitle(path) {
    const regex = /^\/wiki\/(.*)/;

    const match = path.match(regex);

    if (match) {
        const title = match[1];
        console.log("Extracted article title: ", title);

        return title;
    }

    return null;
}

function getLanguages(title, callback) {
    const request_url = `/w/rest.php/v1/page/${title}/links/language`;
    console.log("Request url: ", request_url);

    fetch(request_url)
        .then(response => {
            if (!response.ok) {
                throw new Error("HTTP status code in error: " + response.statusText);
            }
            return response.json();
        })
        .then(data => callback(data))
        .catch(error => {
            console.error("Error: ", error);
        });
}