import * as fs from "fs"
import toml from "toml"
import { schemeMeta } from "./colorSchemes"
import { Meta, Verification } from "./themes/common/colorScheme"
import https from "https"
import crypto from "crypto"

const accepted_licenses_file = `${__dirname}/../../script/licenses/zed-licenses.toml`

// Use the cargo-about configuration file as the source of truth for supported licenses.
function parseAcceptedToml(file: string): string[] {
    let buffer = fs.readFileSync(file).toString()

    let obj = toml.parse(buffer)

    if (!Array.isArray(obj.accepted)) {
        throw Error("Accepted license source is malformed")
    }

    return obj.accepted
}

function checkLicenses(schemeMeta: Meta[], licenses: string[]) {
    for (let meta of schemeMeta) {
        // FIXME: Add support for conjuctions and conditions
        if (licenses.indexOf(meta.license.SPDX) < 0) {
            throw Error(
                `License for theme ${meta.name} (${meta.license.SPDX}) is not supported`
            )
        }
    }
}

function getLicenseText(
    schemeMeta: Meta[],
    callback: (meta: Meta, license_text: string) => void
) {
    for (let meta of schemeMeta) {
        if (typeof meta.license.license_text == "string") {
            callback(meta, meta.license.license_text)
        } else {
            let license_text_obj: Verification = meta.license.license_text
            // The following copied from the example code on nodejs.org:
            // https://nodejs.org/api/http.html#httpgetoptions-callback
            https
                .get(license_text_obj.https_url, (res) => {
                    const { statusCode } = res

                    if (statusCode < 200 || statusCode >= 300) {
                        throw new Error(
                            `Failed to fetch license for: ${meta.name}, Status Code: ${statusCode}`
                        )
                    }

                    res.setEncoding("utf8")
                    let rawData = ""
                    res.on("data", (chunk) => {
                        rawData += chunk
                    })
                    res.on("end", () => {
                        const hash = crypto
                            .createHash("sha256")
                            .update(rawData)
                            .digest("hex")
                        if (license_text_obj.license_checksum == hash) {
                            callback(meta, rawData)
                        } else {
                            throw Error(
                                `Checksum for ${meta.name} did not match file downloaded from ${license_text_obj.https_url}`
                            )
                        }
                    })
                })
                .on("error", (e) => {
                    throw e
                })
        }
    }
}

function writeLicense(schemeMeta: Meta, text: String) {
    process.stdout.write(
        `## [${schemeMeta.name}](${schemeMeta.url})\n\n${text}\n********************************************************************************\n\n`
    )
}

const accepted_licenses = parseAcceptedToml(accepted_licenses_file)
checkLicenses(schemeMeta, accepted_licenses)

getLicenseText(schemeMeta, (meta, text) => {
    writeLicense(meta, text)
})