// SPDX-License-Identifier: AGPL-3.0-or-later

use sha2::{Digest, Sha256};
use std::env;
use std::fs;
use std::path::{Path, PathBuf};
use std::process::Command;

const BUNDLED_FAMILIES: &[&str] = &["FluxerSans", "FluxerMono"];

const BUNDLED_WEIGHTS: &[u64] = &[400, 500, 600, 700];

const EXPECTED_FACE_COUNT: usize = 16;

fn main() {
    let manifest_dir =
        PathBuf::from(env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR missing"));
    let out_dir = PathBuf::from(env::var("OUT_DIR").expect("OUT_DIR missing"));

    println!("cargo:rerun-if-changed=src/styles/app.css");
    println!("cargo:rerun-if-changed=src/");
    println!("cargo:rerun-if-changed=openapi-admin.json");

    generate_admin_api(&manifest_dir, &out_dir);
    build_fonts(&manifest_dir, &out_dir);
    build_tailwind(&manifest_dir, &out_dir);
}

fn generate_admin_api(manifest_dir: &Path, out_dir: &Path) {
    let spec_path = manifest_dir.join("openapi-admin.json");

    if !spec_path.exists() {
        eprintln!("cargo:warning=openapi-admin.json not found, skipping API generation");
        return;
    }

    let json_str = fs::read_to_string(&spec_path).expect("failed to read openapi-admin.json");
    let spec: openapiv3::OpenAPI =
        serde_json::from_str(&json_str).expect("failed to parse openapi-admin.json");

    let mut settings = progenitor::GenerationSettings::new();
    settings.with_interface(progenitor::InterfaceStyle::Positional);

    let mut generator = progenitor::Generator::new(&settings);
    let tokens = generator
        .generate_tokens(&spec)
        .expect("failed to generate admin API client");

    let content = prettyplease::unparse(
        &syn::parse2::<syn::File>(tokens).expect("failed to parse generated tokens"),
    );

    let output_path = out_dir.join("admin_api_generated.rs");
    fs::write(&output_path, content).expect("failed to write generated API code");
}

struct Face {
    css_family: String,
    weight: u64,
    style: String,
    source: String,
}

struct Asset {
    name: String,
    content_type: &'static str,
}

fn build_fonts(manifest_dir: &Path, out_dir: &Path) {
    println!("cargo:rerun-if-changed=../packages/fonts/manifest.json");
    println!("cargo:rerun-if-changed=../packages/fonts/files/FluxerSans");
    println!("cargo:rerun-if-changed=../packages/fonts/files/FluxerMono");
    println!("cargo:rerun-if-changed=../packages/fonts/NOTICE.md");
    println!("cargo:rerun-if-changed=../packages/fonts/LICENSE-IBM-PLEX.txt");

    let package_dir = manifest_dir.join("../packages/fonts");
    let fonts_dir = out_dir.join("static").join("fonts");
    let _ = fs::remove_dir_all(&fonts_dir);
    fs::create_dir_all(&fonts_dir).expect("failed to create generated font dir");

    let mut assets = Vec::new();
    let notice = emit_asset(
        &fonts_dir,
        &package_dir.join("NOTICE.md"),
        "text/plain; charset=utf-8",
        &mut assets,
    );
    let plex_license = emit_asset(
        &fonts_dir,
        &package_dir.join("LICENSE-IBM-PLEX.txt"),
        "text/plain; charset=utf-8",
        &mut assets,
    );

    let faces = select_faces(&package_dir);
    assert_eq!(
        faces.len(),
        EXPECTED_FACE_COUNT,
        "packages/fonts no longer offers the {} Latin-core faces fluxer_admin renders; \
         reconcile BUNDLED_FAMILIES/BUNDLED_WEIGHTS with the manifest",
        EXPECTED_FACE_COUNT
    );

    let mut stylesheet = String::from("/* SPDX-License-Identifier: AGPL-3.0-or-later */\n");
    stylesheet.push_str(
        "/* @generated by fluxer_admin/build.rs from packages/fonts. Do not edit by hand. */\n\n",
    );
    stylesheet.push_str(&format!(
        "/*\n\
         \x20* IBM Plex is licensed under the SIL Open Font License 1.1.\n\
         \x20* The IBM Plex faces below are Modified Versions renamed to \"Fluxer Sans\", so OFL\n\
         \x20* clause 3 requires the disclosure to travel with them. It is served beside them:\n\
         \x20*   ./{notice}\n\
         \x20*   ./{plex_license}\n\
         \x20*\n\
         \x20* Every url() below is relative, so it resolves against this stylesheet's own\n\
         \x20* directory. That keeps the sheet correct under any FLUXER_ADMIN_BASE_PATH without\n\
         \x20* the build having to know the runtime base path.\n\
         \x20*/\n"
    ));
    for face in &faces {
        let source = package_dir.join("files").join(&face.source);
        let file = emit_asset(&fonts_dir, &source, "font/woff2", &mut assets);
        stylesheet.push_str(&format!(
            "@font-face {{\n\
             \tfont-family: '{}';\n\
             \tsrc: url('{file}') format('woff2');\n\
             \tfont-weight: {};\n\
             \tfont-style: {};\n\
             \tfont-display: swap;\n\
             }}\n",
            face.css_family, face.weight, face.style
        ));
    }

    let stylesheet_name = write_hashed(
        &fonts_dir,
        "fonts.css",
        stylesheet.as_bytes(),
        "text/css; charset=utf-8",
        &mut assets,
    );

    write_font_asset_table(out_dir, &stylesheet_name, &assets);
}

fn select_faces(package_dir: &Path) -> Vec<Face> {
    let manifest_path = package_dir.join("manifest.json");
    let raw = fs::read_to_string(&manifest_path).unwrap_or_else(|err| {
        panic!(
            "failed to read {}: {err}. packages/fonts is generated by \
             `python3 tools/fonts/build_fonts.py`.",
            manifest_path.display()
        )
    });
    let manifest: serde_json::Value =
        serde_json::from_str(&raw).expect("failed to parse packages/fonts/manifest.json");
    let families = manifest["families"]
        .as_array()
        .expect("packages/fonts/manifest.json has no families array");

    let mut faces = Vec::new();
    for wanted in BUNDLED_FAMILIES {
        let family = families
            .iter()
            .find(|family| family["id"].as_str() == Some(wanted))
            .unwrap_or_else(|| panic!("packages/fonts/manifest.json has no family {wanted}"));
        assert_eq!(
            family["latinCore"].as_bool(),
            Some(true),
            "{wanted} is no longer a Latin-core family; it would need unicode-range gating"
        );
        let css_family = family["cssFamily"]
            .as_str()
            .unwrap_or_else(|| panic!("{wanted} has no cssFamily"))
            .to_owned();
        for face in family["faces"]
            .as_array()
            .unwrap_or_else(|| panic!("{wanted} has no faces array"))
        {
            let weight = face["weight"].as_u64().expect("face has no weight");
            if !BUNDLED_WEIGHTS.contains(&weight) {
                continue;
            }
            assert!(
                face["unicodeRange"].is_null(),
                "{wanted} face {} carries a unicode-range; Latin-core faces must not",
                face["file"]
            );
            faces.push(Face {
                css_family: css_family.clone(),
                weight,
                style: face["style"]
                    .as_str()
                    .expect("face has no style")
                    .to_owned(),
                source: face["file"].as_str().expect("face has no file").to_owned(),
            });
        }
    }
    faces
}

fn emit_asset(
    fonts_dir: &Path,
    source: &Path,
    content_type: &'static str,
    assets: &mut Vec<Asset>,
) -> String {
    let bytes =
        fs::read(source).unwrap_or_else(|err| panic!("failed to read {}: {err}", source.display()));
    let file_name = source
        .file_name()
        .and_then(|name| name.to_str())
        .unwrap_or_else(|| panic!("{} has no file name", source.display()));
    write_hashed(fonts_dir, file_name, &bytes, content_type, assets)
}

fn write_hashed(
    fonts_dir: &Path,
    file_name: &str,
    bytes: &[u8],
    content_type: &'static str,
    assets: &mut Vec<Asset>,
) -> String {
    let (stem, extension) = file_name
        .rsplit_once('.')
        .unwrap_or_else(|| panic!("{file_name} has no extension to hash around"));
    let digest = Sha256::digest(bytes);
    let hash: String = digest
        .iter()
        .take(8)
        .map(|byte| format!("{byte:02x}"))
        .collect();
    let name = format!("{stem}.{hash}.{extension}");
    fs::write(fonts_dir.join(&name), bytes)
        .unwrap_or_else(|err| panic!("failed to write {name}: {err}"));
    assets.push(Asset {
        name: name.clone(),
        content_type,
    });
    name
}

fn write_font_asset_table(out_dir: &Path, stylesheet_name: &str, assets: &[Asset]) {
    let mut generated = String::from(
        "// @generated by fluxer_admin/build.rs from packages/fonts. Do not edit by hand.\n\n",
    );
    generated.push_str(&format!(
        "/// File name of the content-hashed `@font-face` stylesheet, relative to `/static/fonts/`.\npub const STYLESHEET_FILE_NAME: &str = {stylesheet_name:?};\n\n"
    ));
    generated.push_str("/// `(file name, content type, bytes)` for everything served under `/static/fonts/`.\npub static ASSETS: &[(&str, &str, &[u8])] = &[\n");
    for asset in assets {
        generated.push_str(&format!(
            "    ({:?}, {:?}, include_bytes!(concat!(env!(\"OUT_DIR\"), \"/static/fonts/{}\"))),\n",
            asset.name, asset.content_type, asset.name
        ));
    }
    generated.push_str("];\n");
    fs::write(out_dir.join("static").join("fonts.rs"), generated)
        .expect("failed to write generated font asset table");
}

fn build_tailwind(manifest_dir: &Path, out_dir: &Path) {
    let output_dir = out_dir.join("static");
    fs::create_dir_all(&output_dir).expect("failed to create generated static dir");
    let input = manifest_dir.join("src/styles/app.css");
    let output = output_dir.join("app.css");
    let candidates = [
        manifest_dir.join("node_modules/.bin/tailwindcss"),
        manifest_dir.join("../node_modules/.bin/tailwindcss"),
    ];
    let Some(cli) = candidates.iter().find(|c| c.exists()) else {
        panic!(
            "tailwindcss CLI not found. Run `pnpm install` in fluxer_admin/.\n\
             Searched: {:?}",
            candidates
        );
    };
    let status = Command::new(cli)
        .arg("-i")
        .arg(&input)
        .arg("-o")
        .arg(&output)
        .arg("--minify")
        .arg("--cwd")
        .arg(manifest_dir)
        .status()
        .expect("failed to run tailwindcss");
    if !status.success() {
        panic!("tailwindcss failed with status {}", status);
    }
}