-- Downloads StargateControl files from GitHub into disk/*.lua (or disk2/..., per file_list)

if not http then
    error("HTTP API is disabled")
end

local BASE_URL = "https://raw.githubusercontent.com/APasz/StargateControl/main/"
local COMMITS_API_URL = "https://api.github.com/repos/APasz/StargateControl/commits/main"
local DEFAULT_TARGET_DIR = "disk"
local FILE_LIST_PATH = "sync/file_list.lua"
local UPDATER_PATH = "sync/updater.lua"

local args = { ... }
local self_only = args[1] == "self" or args[1] == "manifest"

local function download(url, headers)
    local res, err = http.get(url, headers)
    if not res then
        return nil, err
    end

    local content = res.readAll()
    res.close()
    return content, nil
end

local function fetch_latest_commit_name()
    local parse_json = textutils.unserialiseJSON
    if not parse_json then
        return nil, "JSON parser unavailable"
    end

    local headers = {
        ["User-Agent"] = "StargateControlUpdater",
        Accept = "application/vnd.github+json",
    }

    local content, err = download(COMMITS_API_URL, headers)
    if not content then
        return nil, err
    end

    local ok, data = pcall(parse_json, content)
    if not ok or type(data) ~= "table" then
        return nil, "Unexpected API response"
    end

    local message = data.commit and data.commit.message
    if type(message) ~= "string" then
        return nil, "Commit message unavailable"
    end

    local subject = message:match("([^\r\n]+)") or message
    return subject
end

local function load_file_list()
    local content, err = download(BASE_URL .. FILE_LIST_PATH)
    if not content then
        error("Failed to download file list: " .. tostring(err), 0)
    end

    local chunk, load_err = load(content, FILE_LIST_PATH, "t", {})
    if not chunk then
        error("Unable to parse file list: " .. tostring(load_err), 0)
    end

    local ok, result = pcall(chunk)
    if not ok then
        error("Failed to load file list: " .. tostring(result), 0)
    end

    if type(result) ~= "table" then
        error("Invalid file list contents", 0)
    end

    return result
end

local function download_file(path, destination, target_dir)
    local url = BASE_URL .. path
    local content, err = download(url)
    if not content then
        print("Failed; " .. path .. ": " .. tostring(err))
        return false
    end

    local base_dir = target_dir or DEFAULT_TARGET_DIR
    local target_path = destination or fs.combine(base_dir, path)
    local dir = fs.getDir(target_path)
    if dir and dir ~= "" then
        fs.makeDir(dir)
    end

    local f = fs.open(target_path, "w")
    if not f then
        print("Failed to open " .. target_path .. " for writing.")
        return false
    end
    f.write(content)
    f.close()

    print("Saved: " .. target_path)
    return true
end

local function collect_files(file_list)
    local files = {}
    local seen = {}

    for _, scope_files in pairs(file_list) do
        for _, file in ipairs(scope_files) do
            local path = file.git
            if path ~= FILE_LIST_PATH then
                local disk = file.disk
                local key = ("%s:%s"):format(disk or "", path)
                if not seen[key] then
                    files[#files + 1] = { path = path, disk = disk }
                    seen[key] = true
                end
            end
        end
    end

    return files
end

local function validate_target_dirs(files)
    local missing = {}

    if not fs.exists(DEFAULT_TARGET_DIR) or not fs.isDir(DEFAULT_TARGET_DIR) then
        missing[DEFAULT_TARGET_DIR] = true
    end

    for _, file in ipairs(files) do
        local base_dir = file.disk or DEFAULT_TARGET_DIR
        if not fs.exists(base_dir) or not fs.isDir(base_dir) then
            missing[base_dir] = true
        end
    end

    if next(missing) then
        local dirs = {}
        for dir in pairs(missing) do
            dirs[#dirs + 1] = dir
        end
        error("Missing target disk directories: " .. table.concat(dirs, ", "), 0)
    end
end

local function resolve_disk_for_file(file)
    return file.disk or DEFAULT_TARGET_DIR
end

local function download_files(files)
    local ok = true
    for _, file in ipairs(files) do
        local disk = resolve_disk_for_file(file)
        ok = download_file(file.path, nil, disk) and ok
    end
    return ok
end

local commit_name, commit_err = fetch_latest_commit_name()

local success = true
if self_only then
    validate_target_dirs({})
    success = download_file(FILE_LIST_PATH, nil, DEFAULT_TARGET_DIR) and success
else
    local file_list = load_file_list()
    local files = collect_files(file_list)
    validate_target_dirs(files)
    success = download_file(FILE_LIST_PATH, nil, DEFAULT_TARGET_DIR) and success
    success = download_files(files) and success
end

success = download_file(UPDATER_PATH, "updater.lua") and success

if success then
    print("Done!")
else
    print("Done (with errors; see above)")
end
if commit_name then
    print(commit_name)
elseif commit_err then
    print("Latest commit unavailable: " .. tostring(commit_err))
end