/* ========================================================================= *\
|* === Signed Integrity: content integrity using signed integrity data   === *|
\* ========================================================================= */

/**
 * signed-integrity plugin's deploy/utility functions
 * 
 * this code expects a Deno runtime:
 * https://deno.land/
 */


/**
 * helper function, converting binary to base64
 * this need not be extremely fast, since it will only be used on digests
 * 
 * binary_data - data to convert to base64
 */
let binToBase64 = (binary_data) => {
    return btoa(
                (new Uint8Array(binary_data))
                    .reduce((bin, byte)=>{
                        return bin += String.fromCharCode(byte)
                    }, '')
            )
}


/**
 * generate an ECDSA P-384 keypair and export it as a JWK
 * https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/importKey#json_web_key
 */
let genKeypair = async () => {
    let keypair = await crypto.subtle.generateKey({
                        name: "ECDSA",
                        namedCurve: "P-384"
                    },
                    true,
                    ["sign", "verify"]
                );
    let exported_keypair = {
        publicKey: await crypto.subtle.exportKey("jwk", keypair.publicKey),
        privateKey: await crypto.subtle.exportKey("jwk", keypair.privateKey)
    }
    return JSON.stringify(exported_keypair)
}

/**
 * get a public key from a provided private key file
 * 
 * keyfile - a path to a file containing the private key
 */
let getPubkey = async (keyfile) => {
    
    // we only want to process one file
    if (Array.isArray(keyfile)) {
        keyfile = keyfile[0]
    }
    // 
    var keydata = JSON.parse(await Deno.readTextFile(keyfile));
    // the key can be either in a CryptoKeyPair structure, or directly in CryptoKey structure
    // standardize!
    if ("privateKey" in keydata) {
        keydata = keydata.privateKey
    }
    
    // make the key public by deleting private parts and modifying key_ops
    // ref. https://stackoverflow.com/a/57571350
    delete keydata.d;
    keydata.key_ops = ['verify']
    
    // import the key, thus making sure data is valid and makes sense
    let key = await crypto.subtle.importKey(
                        "jwk",
                        keydata,
                        {
                            name: 'ECDSA',
                            namedCurve: 'P-384'
                        },
                        true,
                        ['verify']
                    )
    
    // export it again
    return JSON.stringify(await crypto.subtle.exportKey("jwk", key))
}

/**
 * get integrity digests for a given path
 * 
 * path  - path to a file whose digest is to be generated
 * algos - array of SubtleCrypto.digest-compatible algorithm names
 */
let getFileIntegrity = async (path, algos) => {
    
    var result = []
    
    // open the file and get some info on it
    const file = await Deno.open(
                                path,
                                { read: true }
                            );
    const fileInfo = await file.stat();
    
    // are we working with a file?
    if (fileInfo.isFile) {
        
        //console.log(`+-- reading: ${path}`)
        
        // initialize
        var content = new Uint8Array()
        var buf = new Uint8Array(1000);
        
        // read the first batch
        var numread = file.readSync(buf);
        
        // read the rest, if there is anything to read
        while (numread !== null) {
            //console.log(`    +-- read: ${numread}`)
            //console.log(`        +-- length: ${content.length}`)
            
            // there has to be a better way...
            var new_content = new Uint8Array(content.length + numread);
            //console.log(`        +-- new length: ${new_content.length}`)
            new_content.set(content)
            if (buf.length === numread) {
                new_content.set(buf, content.length)
            } else {
                new_content.set(buf.slice(0, numread), content.length)
            }
            content = new_content
            
            // read some more
            numread = file.readSync(buf);
        }
        //console.log('    +-- done.')
        
        //console.log('+-- calculating digests')
        for (const algo of algos) {
            //console.log(`    +-- ${algo}`)
            var digest = algo.toLowerCase().replace('-', '') + '-' + binToBase64(await crypto.subtle.digest(algo, content))
            //console.log(digest)
            result.push(digest)
        }
        //console.log(`+-- file done: ${path}`)
        
    // we are not working with a file
    } else {
        result = false;
    }
    
    // putting this in a try-catch block as the file
    // is apparently being auto-closed?
    // https://issueantenna.com/repo/denoland/deno/issues/15442
    try {
        await file.close();
    } catch (BadResource) {}
    
    // return the result
    return result
}


/**
 * generate integrity files for provided paths
 * 
 * paths     - paths to files for which integrity files are to be generated
 * keyfile   - path of the file containing the private key to use
 * extension - file extension to use when saving integrity files (default: ".integrity")
 */
let genSignedIntegrity = async (paths, keyfile, extension='.integrity') => {
    
    // load the key
    var keydata = JSON.parse(await Deno.readTextFile(keyfile));
    
    // the key can be either in a CryptoKeyPair structure, or directly in CryptoKey structure
    // standardize!
    if ("privateKey" in keydata) {
        keydata = keydata.privateKey
    }
    
    // import the key, thus making sure data is valid and makes sense
    let privkey = await crypto.subtle.importKey(
                            "jwk",
                            keydata,
                            {
                                name: 'ECDSA',
                                namedCurve: 'P-384'
                                
                            },
                            true,
                            ['sign']
                        )
    
    // TODO: implement shit
}

// this never changes
const pluginName = "signed-integrity"
const pluginDescription = "Fetching signed integrity data and using it to verify content.\nCLI used to generate subresource integrity tokens and save them in integrity files."
const pluginVersion = 'COMMIT_UNKNOWN'
const pluginActions = {
    "gen-keypair": {
        run: genKeypair,
        description: "generate a keypair and export it as a JSON Web Key"
    },
    "get-pubkey": {
        run: getPubkey,
        description: "print out a public key derived from the provided private key",
        arguments: {
            '_': {
                name: "keyfile",
                description: "file containing the private key in JSON Web Key format"
            }
        }
    },
    "gen-integrity": {
        run: genSignedIntegrity,
        description: "generate integrity files for given paths",
        arguments: {
            '_': {
                name: "file",
                description: "paths to generate signed integrity files for"
            },
            keyfile: {
                description: "path to the file containing a private key in JSON Web Key format",
                string: true
            },
            extension: {
                description: "file extension to use when saving integrity files",
                default: '.integrity',
                string: true
            }
        }
    }
}

export {
    pluginName as name,
    pluginDescription as description,
    pluginVersion as version,
    pluginActions as actions
}