local vm       = require 'vm'
local util     = require 'utility'
local config   = require 'config'
local infer    = require 'core.infer'
local await    = require 'await'

local function formatKey(key)
    if type(key) == 'string' then
        if key:match '^[%a_][%w_]*$' then
            return key
        else
            return ('[%s]'):format(util.viewLiteral(key))
        end
    end
    return ('[%s]'):format(key)
end

local function buildAsHash(keys, inferMap, literalMap, reachMax)
    local lines = {}
    lines[#lines+1] = '{'
    for _, key in ipairs(keys) do
        local inferView   = inferMap[key]
        local literalView = literalMap[key]
        if literalView then
            lines[#lines+1] = ('    %s: %s = %s,'):format(formatKey(key), inferView, literalView)
        else
            lines[#lines+1] = ('    %s: %s,'):format(formatKey(key), inferView)
        end
    end
    if reachMax > 0 then
        lines[#lines+1] = ('    ...(+%d)'):format(reachMax)
    end
    lines[#lines+1] = '}'
    return table.concat(lines, '\n')
end

local function buildAsConst(keys, inferMap, literalMap, reachMax)
    table.sort(keys, function (a, b)
        return tonumber(literalMap[a]) < tonumber(literalMap[b])
    end)
    local lines = {}
    lines[#lines+1] = '{'
    for _, key in ipairs(keys) do
        local inferView   = inferMap[key]
        local literalView = literalMap[key]
        if literalView then
            lines[#lines+1] = ('    %s: %s = %s,'):format(formatKey(key), inferView, literalView)
        else
            lines[#lines+1] = ('    %s: %s,'):format(formatKey(key), inferView)
        end
    end
    if reachMax > 0 then
        lines[#lines+1] = ('    ...(+%d)'):format(reachMax)
    end
    lines[#lines+1] = '}'
    return table.concat(lines, '\n')
end

local typeSorter = {
    ['string']  = 1,
    ['number']  = 2,
    ['boolean'] = 3,
}

local function getKeyMap(fields)
    local keys = {}
    local mark = {}
    for _, field in ipairs(fields) do
        local key = vm.getKeyName(field)
        local tp  = vm.getKeyType(field)
        if tp == 'number' or tp == 'integer' then
            key = tonumber(key)
        elseif tp == 'boolean' then
            key = key == 'true'
        end
        if key and not mark[key] then
            mark[key] = true
            keys[#keys+1] = key
        end
    end
    table.sort(keys, function (a, b)
        local ta = typeSorter[type(a)]
        local tb = typeSorter[type(b)]
        if ta == tb then
            return tostring(a) < tostring(b)
        else
            return ta < tb
        end
    end)
    return keys
end

return function (source)
    local maxFields = config.get 'Lua.hover.previewFields'
    if maxFields <= 0 then
        return 'table'
    end

    local fields = vm.getRefs(source, '*')
    local keys   = getKeyMap(fields)

    if #keys == 0 then
        return '{}'
    end

    local inferMap   = {}
    local literalMap = {}

    local reachMax = #keys - maxFields
    if #keys > maxFields then
        for i = maxFields + 1, #keys do
            keys[i] = nil
        end
    end

    local isConsts = true
    for i = 1, #keys do
        await.delay()
        local key = keys[i]
        inferMap[key]   = infer.searchAndViewInfers(source, key)
        literalMap[key] = infer.searchAndViewLiterals(source, key)
        if not tonumber(literalMap[key]) then
            isConsts = false
        end
    end

    local result

    if isConsts then
        result = buildAsConst(keys, inferMap, literalMap, reachMax)
    else
        result = buildAsHash(keys, inferMap, literalMap, reachMax)
    end

    --if timeUp then
    --    result = ('\n--%s\n%s'):format(lang.script.HOVER_TABLE_TIME_UP, result)
    --end

    return result
end