local dir = require "pl.dir"
local path = require "pl.path"

local term = require "volksdata.term"
local nsm = require "volksdata.namespace"

local pkar = require "pocket_archive"
local logger = pkar.logger


-- "nil" table.
local NT = {}

local no_ll_pnames = {
    archive_path = true,
    checksum = true,
    size = true,
    submitted = true,
    sub_id = true,
}


local M = {
    -- Parsed typedef configurations.
    types = {},

    -- Field names. Order is kept in encoding laundry lists. The hardcoded
    -- values come first, all others are harvested from the typedef
    -- configuration and ordered alphabetically.
    pnames = {"content_type", "id", "source_path"},

    -- Term-to-URI map. URIs are volksdata.Term objects.
    id_to_uri = {},

    -- URI-to-term map. Keys are URI strings, not volksdata.Term objects,
    -- because key comparison wouldn't work with them.
    uri_to_id = {},
}

M.from_uri = function(type_uri)
    assert(type_uri)
    return M.types[M.uri_to_id[nsm.denormalize_uri(type_uri.data)]]
end


-- Parameters that do not get inherited.
local NO_INHERIT = {abstract = true}
local MODEL_PATH = path.join(pkar.config_path, "model")

local gen_config = dofile(path.join(MODEL_PATH, "generation.lua"))


local function add_term(id, uri_str)
    --if not uri then error(("Term %s has not a URI!"):format(term), 2) end
    if not uri_str then return end
    local uri = term.new_iriref_ns(uri_str)
    if not M.id_to_uri[id] then M.id_to_uri[id] = uri end
    if not M.uri_to_id[uri_str] then M.uri_to_id[uri_str] = id end
end


local function parse_model(mod_id)
    local hierarchy = {}

    local function traverse(mod_id)
        logger:debug("traversing: " .. mod_id)
        local model = dofile(path.join(
                MODEL_PATH, "typedef", mod_id .. ".lua"))
        -- Merge separate generator config
        model.gen = gen_config[mod_id]
        --model.id = mod_id
        --print("Model: ")
        --for k, v in pairs(model) do print (k, v) end

        -- Prepend to hierarchy.
        model.id = mod_id

        -- Store term-to-URI and URI-to-term mappings.
        add_term(model.id, model.uri)
        for prop, pdata in pairs(model.properties or {}) do
            add_term(prop, pdata.uri) end

        table.insert(hierarchy, 1, model)

        if model.broader then traverse(model.broader) end
    end
    traverse(mod_id)

    local lineage = {}  -- Ordered lineage of types, from ancestor to leaf.
    local types = {}  -- Set of all types.
    for _, mod in ipairs(hierarchy) do
        table.insert(lineage, mod.id)
        types[mod.id] = true
    end

    local function merge(src, dest)
        for k, v in pairs(src) do
            if NO_INHERIT[k] then goto continue end
            if type(v) == "table" then
                dest[k] = dest[k] or {}
                assert(type(dest[k]) == "table")
                merge(v, dest[k])
            else
                dest[k] = v
            end
            ::continue::
        end
    end
    local config = {lineage = lineage, types = types}

    for _, src_config in ipairs(hierarchy) do
        merge(src_config, config)
    end

    return config
end


local function setup_model()
    -- Temp store (set) for property names.
    local all_pnames = {}
    -- Collect all type names from config file names.
    for _, fpath in ipairs(dir.getfiles(
                path.join(MODEL_PATH, "typedef"), "*.lua")) do
        local mname = path.basename(fpath):gsub(".lua$", "")
        local typedef = parse_model(mname)

        -- Store parsed typedef configurations.
        M.types[mname] = typedef

        -- Store unique prop names.
        for pn in pairs(typedef.properties or NT) do
            if not no_ll_pnames[pn] then all_pnames[pn] = true end
        end
    end

    -- Remove hardcoded prop names, reorder, and append to module's pnames.
    local pnames_ordered = {}
    for _, hcpn in ipairs(M.pnames) do
        all_pnames[hcpn] = nil
    end
    for pn in pairs(all_pnames) do
        table.insert(pnames_ordered, pn)
    end
    table.sort(pnames_ordered)
    for _, pn in ipairs(pnames_ordered) do table.insert(M.pnames, pn) end
    logger:debug("Property names ordered: " .. table.concat(M.pnames, ", "))
end


setup_model()

return M