let exported = {};
let patchType = null
process.env.PATCHTYPE = null;
global.patchType = null;

if(typeof global.fetch === "function"){
    // checking if the native fetch api is supported, if yes exporting it.
    //if this throws an error:
    // nodejs api's fetch function is not available.
    // trying node-fetch
    global.fetch.patchType = 0;
    exported = global.fetch;
    patchType = 0;
    process.env.PATCHTYPE = 0;
    global.patchType = 0;
}
else{
    // nodejs native fetch api not found, trying to use node-fetch
    try{
        require.resolve("node-fetch");
        const nodeFetch2 = require("node-fetch")
        exported = nodeFetch2
        // checking for node-fetch@=<2.6.1, if found exporting it.
        // if this throws an error:
        // commonJS require for node-fetch is not available, so node-fetch doesn't exist or its version is higher than 2.6.1 
        // trying to import node-fetch using commonJS import
        patchType = 2;
        process.env.PATCHTYPE = 2;
        global.patchType = 2;
    }
    catch(err){
        try{
            require.resolve("node-fetch")
            const nodeFetch = (...args) => import('node-fetch').then(({default: fetch}) => fetch(...args));
            exported = nodeFetch;
            // if this throws an error:
            // any version of node-fetch or native fetch api is not available 
            // trying to install node-fetch with node package manager
            patchType = 3;
            process.env.PATCHTYPE = 3;
            global.patchType = 3;
        }
        catch(error){
            // using npm to install node-fetch
                patchType = undefined;
                delete process.env.PATCHTYPE;
                global.patchType = undefined;
            require("child_process").exec("npm install node-fetch", (err, stdout, stderr) => {
                if(err) console.error(err)
                if(stderr) console.log(stderr)
                if(stdout) console.log(stdout)
                if(!require.main){
                    require("child_process").spawn(process.execPath, [],{
                        cwd: process.cwd (),
                        detached: true,
                        stdio: 'inherit'
                    });
                    console.log("[node-fetch-patch] restarting node console")
                }
                else{
                    require("child_process").spawn(process.execPath, [require.main.filename],{
                        cwd: process.cwd (),
                        detached: true,
                        stdio: 'inherit'
                    });
                    console.log("[node-fetch-patch] restarting " + require.main.filename)
                }
            })
        }
    }
}
// exporting the found fetch method
module.exports = exported
module.exports.patchType = patchType