using Pkg
using Pkg.TOML
using LibGit2

const base = ["Base64",
              "CRC32c",
              "Dates",
              "DelimitedFiles",
              "Distributed",
              "FileWatching",
              "Future",
              "InteractiveUtils",
              "Libdl",
              "LibGit2",
              "LinearAlgebra",
              "Logging",
              "Markdown",
              "Mmap",
              "Pkg",
              "Printf",
              "Profile",
              "Random",
              "REPL",
              "Serialization",
              "SHA",
              "SharedArrays",
              "Sockets",
              "SparseArrays",
              "Statistics",
              "SuiteSparse",
              "Test",
              "Unicode",
              "UUIDs"]
const disabled = ["WinRPM", "Homebrew", "CMake",
                  "Docile", "Color", 
                  "HTTPClient", "ICU", "Calendar", "LegacyStrings",
                  "Nulls"]

registrypath = expanduser("~/.julia-old/registries/General/")
registry = joinpath(registrypath, "Registry.toml")
const register = TOML.parse(join(readlines(registry), "\n"))

jlpkgname(info) = "julia-$(lowercase(info.name))"

function getrev(path)
    versions = TOML.parse(join(readlines(path), "\n"))
    versionv = findmax(map(x -> VersionNumber(x), keys(versions) |> collect))
    (rev = versions[string(versionv[1])]["git-tree-sha1"],
     ver = versionv[1])
end

function getpackagebyuuid(uuid)
    uuid in keys(register["packages"]) || return nothing
    path = register["packages"][uuid]["path"]
    getpath(x) =  joinpath(registrypath, joinpath(path, x))
    package = TOML.parse(join(readlines(getpath("Package.toml")), "\n"))
    deppath = getpath("Deps.toml")
    isfile(deppath) || return nothing
    deps = TOML.parse(join(readlines(deppath), "\n"))
    (name = package["name"],
     uuid = package["uuid"],
     repo = package["repo"],
     deps = deps,
     vers = getrev(getpath("Versions.toml")))
end

function getpackage(wanted)
    uuid = findfirst(p -> lowercase(p["name"]) == lowercase(wanted),
                     register["packages"])
    uuid == nothing && return nothing
    return getpackagebyuuid(uuid)
end

function getdeps!(deps, vers, recursive, out)
    flat(arr::Array) = mapreduce(x -> isa(x, Array) ? flat(x) : x, append!,
                                 arr, init=[])
    v = map(p -> VersionNumber.(split(p, '-')), keys(deps) |> collect)
    valid = findall(x -> length(x) == 1 ||
                    (x[2] == v"0" && x[1] <= vers) ||
                    x[1] <= vers <= x[2], v)
    f = flat(map(x -> values(x), values(collect(values(deps))[valid])))
    push!.(Ref(out), f)
    # if recursive
    #     push!
    # end
    nothing
end

function have(info)
    file = "/home/nixo/git/guix/gnu/packages/julia-xyz.scm"
    return "(name \"" * jlpkgname(info) * "\")" in strip.(readlines(file))
end

function gethash(info)
    wd = mktempdir()
    if info.name in base ||
        info.name in disabled ||
        have(info)
        return ""
    end
    println(stderr, "Cloning $(info.name) in $wd")
    repo = LibGit2.clone(info.repo, wd)
    hash = cd(wd) do
        out = Pipe()
        try
            LibGit2.checkout!(repo,
                              string(LibGit2.GitHash(LibGit2.peel(LibGit2.GitCommit,
                                                                  LibGit2.GitTag(repo, "v" * string(info.vers.ver))))))
        catch e
            try
                LibGit2.checkout!(repo,
                                  string(LibGit2.GitHash(LibGit2.peel(LibGit2.GitCommit,
                                                                      LibGit2.GitCommit(repo, "v" * string(info.vers.ver))))))
            catch e
                # FIXME: if this happens, return the commit too and use it in the package
                println(stderr, "Failed to checkout $(e), continuing")
            end
        end
        run(pipeline(`guix hash -rx .`, stdout=out))
        readline(out)
    end
    rm(wd, recursive = true)
    hash
end

function makepackage(info; done = [])
    if info === nothing
        @warn "Could not find package (have you cloned the registry?)"
        return
    elseif info in done
        return ""
    end
    push!(done, info)
    deps = String[]
    getdeps!(info.deps, info.vers.ver, true, deps)
    # TODO: remove deps that are in base
    deps = filter(x -> x !== nothing, getpackagebyuuid.(deps))
    deplist = join(map(name -> "(\"$name\" ,$name)",
                       jlpkgname.(deps)), '\n')
    packagedeps = join(makepackage.(deps, done = done), "")
    hash = gethash(info)
    hash == "" && return ""
    """
    $packagedeps
    (define-public $(jlpkgname(info))
      (package
       (name "$(jlpkgname(info))")
       (version "$(info.vers.ver)")
       (source
          (origin
            (method git-fetch)
            (uri (git-reference
              (url "$(info.repo)")
              (commit (string-append "v" version))))
            (file-name "$(info.name)")
            (sha256
                 (base32 "$hash"))))
       (propagated-inputs `($(deplist)))
       (build-system julia-build-system)
       (home-page "$(info.repo)")
       (synopsis "")
       (description "")
       (license license:expat)))
    """
end

println.(makepackage.(getpackage.(ARGS)))