import { AutomaticLinkerSettings } from "../settings/settings-info"

type GitHubURLInfo = {
    owner: string
    repository: string
    type?: "pull" | "issues"
    id?: string
}

/**
 * Format a GitHub URL by normalizing the format and converting to Obsidian link format:
 * [[github_id/repository/{pull or issue}/{id}]] [🔗](url)
 * @param url The URL to format
 * @param settings Plugin settings
 * @returns The formatted URL in Obsidian link format
 */
export function formatGitHubURL(
    url: string,
    settings: AutomaticLinkerSettings,
): string {
    try {
        const githubURL = new URL(url)

        // Check if it's a GitHub URL (including Enterprise)
        if (!isGitHubURL(githubURL, settings.githubEnterpriseURLs)) {
            return url
        }

        const urlInfo = parseGitHubURL(githubURL)
        if (!urlInfo) {
            return url
        }

        const cleanURL = getCleanURL(githubURL, urlInfo)
        return formatToObsidianLink(urlInfo, cleanURL)
    }
    catch {
        // If URL is invalid, return original string
        return url
    }
}

/**
 * Parse GitHub URL into its components
 */
function parseGitHubURL(url: URL): GitHubURLInfo | null {
    const parts = url.pathname.split("/").filter(Boolean)
    if (parts.length < 2) {
        return null
    }

    const [owner, repository, type, id] = parts
    const urlInfo: GitHubURLInfo = {
        owner,
        repository,
    }

    if (isPullRequestOrIssueURL(url)) {
        urlInfo.type = type as "pull" | "issues"
        urlInfo.id = id
    }

    return urlInfo
}

/**
 * Get clean URL without query parameters and trailing slashes
 */
function getCleanURL(url: URL, urlInfo: GitHubURLInfo): string {
    if (urlInfo.type && urlInfo.id) {
        const basePath = `/${urlInfo.owner}/${urlInfo.repository}/${urlInfo.type}/${urlInfo.id}`
        return `${url.origin}${basePath}`
    }
    return `${url.origin}/${urlInfo.owner}/${urlInfo.repository}`.replace(
        /\/$/,
        "",
    )
}

/**
 * Format URL info into Obsidian link format
 */
function formatToObsidianLink(
    urlInfo: GitHubURLInfo,
    cleanURL: string,
): string {
    const url = new URL(cleanURL)
    const isEnterpriseURL = url.hostname !== "github.com"
    const prefix = isEnterpriseURL ? "ghe" : "github"

    let wikiLink = `[[${prefix}/${urlInfo.owner}/${urlInfo.repository}`
    if (urlInfo.type && urlInfo.id) {
        wikiLink += `/${urlInfo.type}/${urlInfo.id}`
    }
    wikiLink += `]] [🔗](${cleanURL})`
    return wikiLink
}

/**
 * Check if the URL is a GitHub URL (including Enterprise)
 */
function isGitHubURL(url: URL, enterpriseURLs: string[]): boolean {
    // Check if it's github.com
    if (url.hostname === "github.com") {
        return true
    }

    // Check if it matches any of the configured enterprise URLs
    return enterpriseURLs.some((enterpriseURL) => {
        // Remove any protocol and trailing slashes from the enterprise URL
        const cleanEnterpriseURL = enterpriseURL
            .replace(/^https?:\/\//, "")
            .replace(/\/$/, "")
        return url.hostname === cleanEnterpriseURL
    })
}

/**
 * Check if the URL is a pull request or issue URL
 */
function isPullRequestOrIssueURL(url: URL): boolean {
    const path = url.pathname.toLowerCase()
    return path.includes("/pull/") || path.includes("/issues/")
}