VERSION = "2.2.0"

---- `0` = The value 0 if `version1` is the same as `version2`
---- `-1` = The value less than 0 if `version1` is older than `version2`
---- `1` = The value greater than 0 if `version1` newer than `version2  `
---@param version1 string
---@param version2 string
---@return -1|0|1
local function compare_version_to(version1, version2)
    local major1, minor1, patch1 = version1:match("(%d+)%.(%d+)%.(%d+)")
    local major2, minor2, patch2 = version2:match("(%d+)%.(%d+)%.(%d+)")

    -- There's probably a better way, but I'm lazy atm :P
    if major1 > major2 then return 1 end
    if major1 < major2 then return -1 end

    if minor1 > minor2 then return 1 end
    if minor1 < minor2 then return -1 end

    if patch1 > patch2 then return 1 end
    if patch1 < patch2 then return -1 end

    return 0
end

------------------------
-- Migration Functions
------------------------

-- 2.1.X -> 2.2.0
-- Release all world objects to migrate old saves to use the
-- per-object spawning system instead
local function migrate_world_objects()
    local hf_obj_spawned = alife_storage_manager.get_state().hf_obj_spawned
    if not hf_obj_spawned then return end

    alife():iterate_objects(function(se_obj)
        local data = hf_obj_manager.get_data(se_obj.id)

        if data and data.is_world_obj then
            alife_release(se_obj, "[HF] Releasing old world object with id " .. se_obj.id)
        end
    end)

    alife_storage_manager.get_state().hf_obj_spawned = nil
end

-- pre-2.0.0
-- Initialise metadata
local function reinit_obj_data()
    local sim = alife()
    for i=1,65534 do
        local se_obj = sim:object(i)
        if se_obj then
            local placeable_type = hf_furniture_types.get_type(se_obj)
            if placeable_type then
                -- Initialise data store
                hf_obj_manager.set_data(se_obj.id, {})

                if placeable_type == "light" then
                    -- Switch off light when it is online
                    hf_obj_manager.update_data(obj_id, {is_on=false})
                end
            end
        end
    end
end

----------------------------------------------------------------
-- Generic functions to migrate save based on semver versioning
----------------------------------------------------------------

-- Array of functions for migrating from old versions
-- Assumed to be sorted already
local migration_functions = {
    {
        version = "2.1.0",
        functor = reinit_obj_data,
    },
    {
        version = "2.2.0",
        functor = migrate_world_objects,
    }
}

---@return number|nil
local function get_starting_migration_i(version)
    for i, migration_function_data in ipairs(migration_functions) do
        -- Exit if current version is older than a version with migrate function
        if compare_version_to(version, migration_function_data.version) == -1 then
            return i
        end
    end
end

---@param version string
local function migrate_save(version)
    local start_i = get_starting_migration_i(version)
    if not start_i then return end

    for i=start_i, #migration_functions do
        migration_functions[i].functor()
    end
end

-------------
-- Callbacks
-------------

function save_state(mdata)
    mdata.hf_version = VERSION
end

function actor_on_init()
    local save_hf_version = alife_storage_manager.get_state().hf_version
    if not save_hf_version or save_hf_version ~= VERSION then
        -- Save has a different version from that which is loaded
        migrate_save(save_hf_version or "0.0.0")
    end
end

function on_game_start()
    RegisterScriptCallback("save_state", save_state)
    RegisterScriptCallback("actor_on_init", actor_on_init)
end