import type {AstroIntegration, ContentEntryType, HookParameters} from "astro"
import {fileURLToPath} from "url"
import {parse as parseYaml} from "yaml"

export interface GemtextConfig {}

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

                        data["title"] =
                            data["title"] ??
                            lines
                                .slice(bodyStartLineIndex)
                                .find((line) => line.startsWith("# "))
                                ?.slice(2)
                        data["pubDate"] =
                            data["pubDate"] ??
                            validDateOrUndefined(
                                lines
                                    .slice(bodyStartLineIndex)
                                    .find((line) => line.startsWith("Published on: "))
                                    ?.slice(14),
                            ) ??
                            validDateOrUndefined(filename.replace(/\.[^.]\+$/, "")) ??
                            validDateOrUndefined(slug.replace(/\.[^.]\+$/, ""))
                        data["updatedDate"] =
                            data["updatedDate"] ??
                            validDateOrUndefined(
                                lines
                                    .slice(bodyStartLineIndex)
                                    .find((line) => line.startsWith("Updated on: "))
                                    ?.slice(14),
                            )

                        return {
                            data,
                            rawData: frontmatter,
                            body,
                            slug,
                        }
                    },
                })
            },
        },
    }
}

const validDateOrUndefined = (x: unknown) => {
    const d = new Date(x as string)
    if (isNaN(d.valueOf())) {
        return undefined
    }
    return d
}