import type {AstroIntegration, ContentEntryType, HookParameters} from "astro"
import {fileURLToPath} from "url"
import gemtextVitePlugin from "./vitePlugin.js"
import {parse as parseYaml} from "yaml"

/** Gemtext configuration options */
export interface GemtextConfig {
    /** Absolute import path to the layout to use for all gemtext pages.
     * If not provided, HMR and the Astro toolbar will not work. (default: none) */
    layout?: string
    /** The format to use for the page title. Can be one of:
     * - `first-heading`: The first heading in the document will be used as the title. (default)
     * - `filename`: The filename of the document will be used as the title.
     */
    titleFormat?: "first-heading" | "filename"
}

type SetupHookParams = HookParameters<"astro:config:setup"> & {
    // `addPageExtension` and `contentEntryType` are not a public APIs
    // Add type defs here
    addPageExtension: (extension: string) => void
    addContentEntryType: (contentEntryType: ContentEntryType) => void
}

export default function gemtext(config: GemtextConfig = {}): AstroIntegration {
    if (!config.titleFormat) {
        config.titleFormat = "first-heading"
    }
    return {
        name: "astro-gemtext",
        hooks: {
            "astro:config:setup": async (_params) => {
                const params = _params as SetupHookParams
                params.addPageExtension(".gmi")
                params.addContentEntryType({
                    extensions: [".gmi"],
                    getRenderFunction: async (config) => {
                      return async (entry) => ({
                        html: entry.body ?? '',
                        frontmatter: entry.data,
                      });
                    },
                    getEntryInfo: async ({fileUrl, contents}) => {
                        const lines = contents.split("\n")
                        let data: Record<string, unknown> = {}
                        let frontmatter = ""
                        let bodyStartLineIndex = 0

                        if (lines.at(0) === "---" && lines.lastIndexOf("---") > 0) {
                            bodyStartLineIndex = lines.indexOf("---", 1) + 1
                            frontmatter = lines
                                .slice(1, bodyStartLineIndex - 1)
                                .join("\n")
                            try {
                                data = {
                                    ...data,
                                    ...parseYaml(frontmatter, {schema: "yaml-1.1"}),
                                }
                            } catch (e) {
                                console.debug(
                                    "Failed to parse YAML frontmatter in gemtext:",
                                    e,
                                )
                            }
                        }

                        const body = lines.slice(bodyStartLineIndex).join("\n")

                        const slug =
                            typeof data["slug"] === "string" ?
                                data["slug"]
                            :   fileURLToPath(fileUrl).slice(
                                    fileURLToPath(fileUrl).lastIndexOf("/") + 1,
                                )

                        return {
                            data,
                            rawData: frontmatter,
                            body,
                            slug,
                        }
                    },
                })
                params.updateConfig({
                    vite: {
                        plugins: [gemtextVitePlugin(config)],
                    },
                })
            },
        },
    }
}