-- UnitTester provides unit testing for other Lua scripts. For details see [[Wikipedia:Lua#Unit_testing]].
-- For user documentation see talk page.
local UnitTester = {}

local frame, tick, cross
local result_table_header = "{|class=\"wikitable\"\n! !! Text !! Expected !! Actual"
local result_table = ''
local num_failures = 0

function first_difference(s1, s2)
    if s1 == s2 then return '' end
    local max = math.min(#s1, #s2)
    for i = 1, max do
        if s1:sub(i,i) ~= s2:sub(i,i) then return i end
    end
    return max + 1
end

function UnitTester:preprocess_equals(text, expected, options)
    local actual = frame:preprocess(text)
    if actual == expected then
        result_table = result_table .. '| ' .. tick
    else
        result_table = result_table .. '| ' .. cross
        num_failures = num_failures + 1
    end
    local nowiki_open = (options and options.nowiki) and '<nowiki>' or ''
    local nowiki_close = (options and options.nowiki) and '</nowiki>' or ''
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected, actual)) or ''
    result_table = result_table .. ' \n| <nowiki>' .. text:gsub('%|', '&#124;') .. '</nowiki> \n| ' .. nowiki_open .. expected .. nowiki_close .. ' \n| ' .. nowiki_open .. actual .. nowiki_close .. differs_at .. "\n|-\n"
end

function UnitTester:preprocess_equals_many(prefix, suffix, cases, options)
    for _, case in ipairs(cases) do
        self:preprocess_equals(prefix .. case[1] .. suffix, case[2], options)
    end
end

function UnitTester:preprocess_equals_preprocess(text1, text2, options)
    local actual = frame:preprocess(text1)
    local expected = frame:preprocess(text2)
    if actual == expected then
        result_table = result_table .. '| ' .. tick
    else
        result_table = result_table .. '| ' .. cross
        num_failures = num_failures + 1
    end
    local nowiki_open = (options and options.nowiki) and '<nowiki>' or ''
    local nowiki_close = (options and options.nowiki) and '</nowiki>' or ''
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected, actual)) or ''
    result_table = result_table .. ' \n| <nowiki>' .. text1:gsub('%|', '&#124;') .. '</nowiki> \n| ' .. nowiki_open .. expected .. nowiki_close .. ' \n| ' .. nowiki_open .. actual .. nowiki_close .. differs_at .. "\n|-\n"
end

function UnitTester:preprocess_equals_preprocess_many(prefix1, suffix1, prefix2, suffix2, cases, options)
    for _, case in ipairs(cases) do
        self:preprocess_equals_preprocess(prefix1 .. case[1] .. suffix1, prefix2 .. (case[2] and case[2] or case[1]) .. suffix2, options)
    end
end

function UnitTester:equals(name, actual, expected, options)
    if actual == expected then
        result_table = result_table .. '| ' .. tick
    else
        result_table = result_table .. '| ' .. cross
        num_failures = num_failures + 1
    end
    local nowiki_open = (options and options.nowiki) and '<nowiki>' or ''
    local nowiki_close = (options and options.nowiki) and '</nowiki>' or ''
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected, actual)) or ''
    result_table = result_table .. ' \n| ' .. name .. ' \n| ' .. nowiki_open .. tostring(expected) .. nowiki_close .. ' \n| ' .. nowiki_open .. tostring(actual) .. nowiki_close .. differs_at .. "\n|-\n"
end

local function deep_compare(t1, t2, ignore_mt)
    local ty1 = type(t1)
    local ty2 = type(t2)
    if ty1 ~= ty2 then return false end
    if ty1 ~= 'table' and ty2 ~= 'table' then return t1 == t2 end
    
    local mt = getmetatable(t1)
    if not ignore_mt and mt and mt.__eq then return t1 == t2 end
    
    for k1, v1 in pairs(t1) do
        local v2 = t2[k1]
        if v2 == nil or not deep_compare(v1, v2) then return false end
    end
    for k2, v2 in pairs(t2) do
        local v1 = t1[k2]
        if v1 == nil or not deep_compare(v1, v2) then return false end
    end

    return true
end

function val_to_str(v)
    if type(v) == 'string' then
        v = mw.ustring.gsub(v, '\n', '\\n')
        if mw.ustring.match(mw.ustring.gsub(v, '[^\'"]', ''), '^"+$') then
            return "'" .. v .. "'"
        end
        return '"' .. mw.ustring.gsub(v, '"', '\\"' ) .. '"'
    else
        return type(v) == 'table' and table_to_str(v) or tostring(v)
    end
end

function table_key_to_str(k)
    if type(k) == 'string' and mw.ustring.match(k, '^[_%a][_%a%d]*$') then
        return k
    else
        return '[' .. val_to_str(k) .. ']'
    end
end

function table_to_str(tbl)
    local result, done = {}, {}
    for k, v in ipairs(tbl) do
        table.insert(result, val_to_str(v))
        done[k] = true
    end
    for k, v in pairs(tbl) do
        if not done[k] then
            table.insert(result, table_key_to_str(k) .. '=' .. val_to_str(v))
        end
    end
    return '{' .. table.concat(result, ',') .. '}'
end

function UnitTester:equals_deep(name, actual, expected, options)
    if deep_compare(actual, expected) then
        result_table = result_table .. '| ' .. tick
    else
        result_table = result_table .. '| ' .. cross
        num_failures = num_failures + 1
    end
    local nowiki_open = (options and options.nowiki) and '<nowiki>' or ''
    local nowiki_close = (options and options.nowiki) and '</nowiki>' or ''
    local actual_str = val_to_str(actual)
    local expected_str = val_to_str(expected)
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected_str, actual_str)) or ''
    result_table = result_table .. ' \n| ' .. name .. ' \n| ' .. nowiki_open .. expected_str .. nowiki_close .. ' \n| ' .. nowiki_open .. actual_str .. nowiki_close .. differs_at .. "\n|-\n"
end

function UnitTester:run(frame_arg)
    frame = frame_arg
    self.frame = frame
    self.differs_at = frame.args['differs_at']
    tick = frame:preprocess('{{Tick}}')
    cross = frame:preprocess('{{Cross}}')

    local table_header = result_table_header
    if self.differs_at then
        table_header = table_header .. ' !! Differs at'
    end

    -- Sort results into alphabetical order.
    local self_sorted = {}
    for key,value in pairs(self) do
        if key:find('^test') then
            table.insert(self_sorted, key)
        end
    end
    table.sort(self_sorted)
    -- Add results to the results table.
    for i,value in ipairs(self_sorted) do
        result_table = result_table .. "'''" .. value .. "''':\n" .. table_header .. "\n|-\n"
        self[value](self)
        result_table = result_table .. "|}\n\n"    
    end

    return (num_failures == 0 and "<font color=\"#008000\">'''All tests passed.'''</font>" or "<font color=\"#800000\">'''" .. num_failures .. " tests failed.'''</font>") .. "\n\n" .. frame:preprocess(result_table)
end

function UnitTester:new()
    local o = {}
    setmetatable(o, self)
    self.__index = self
    return o
end

local p = UnitTester:new()
function p.run_tests(frame) return p:run(frame) end
return p