--[[
The MIT License

Copyright (c) 2009-2012 [Norman Clarke](mailto:norman@njclarke.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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copies or substantial portions of the Software.

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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
]]--

--- Telescope is a test library for Lua that allows for flexible, declarative
-- tests. The documentation produced here is intended largely for developers
-- working on Telescope.  For information on using Telescope, please visit the
-- project homepage at: <a href="http://github.com/norman/telescope">http://github.com/norman/telescope#readme</a>.
-- @release 0.6
-- @class module
-- @module 'telescope'
local _M = {}

local compat_env = require 'compat_env'

local getfenv = _G.getfenv or compat_env.getfenv
local setfenv = _G.setfenv or compat_env.setfenv


local _VERSION = "0.6.0"

--- The status codes that can be returned by an invoked test. These should not be overidden.
-- @name status_codes
-- @class table
-- @field err - This is returned when an invoked test results in an error
-- rather than a passed or failed assertion.
-- @field fail - This is returned when an invoked test contains one or more failing assertions.
-- @field pass - This is returned when all of a test's assertions pass.
-- @field pending - This is returned when a test does not have a corresponding function.
-- @field unassertive - This is returned when an invoked test does not produce
-- errors, but does not contain any assertions.
local status_codes = {
  err         = 2,
  fail        = 4,
  pass        = 8,
  pending     = 16,
  unassertive = 32
}

--- Labels used to show the various <tt>status_codes</tt> as a single character.
-- These can be overidden if you wish.
-- @name status_labels
-- @class table
-- @see status_codes
-- @field status_codes.err         'E'
-- @field status_codes.fail        'F'
-- @field status_codes.pass        'P'
-- @field status_codes.pending     '?'
-- @field status_codes.unassertive 'U'

local status_labels = {
  [status_codes.err]         = 'E',
  [status_codes.fail]        = 'F',
  [status_codes.pass]        = 'P',
  [status_codes.pending]     = '?',
  [status_codes.unassertive] = 'U'
}

--- The default names for context blocks. It defaults to "context", "spec" and
-- "describe."
-- @name context_aliases
-- @class table
local context_aliases = {"context", "describe", "spec"}
--- The default names for test blocks. It defaults to "test," "it", "expect",
-- "they" and "should."
-- @name test_aliases
-- @class table
local test_aliases    = {"test", "it", "expect", "should", "they"}

--- The default names for "before" blocks. It defaults to "before" and "setup."
-- The function in the before block will be run before each sibling test function
-- or context.
-- @name before_aliases
-- @class table
local before_aliases  = {"before", "setup"}

--- The default names for "after" blocks. It defaults to "after" and "teardown."
-- The function in the after block will be run after each sibling test function
-- or context.
-- @name after_aliases
-- @class table
local after_aliases  = {"after", "teardown"}

-- Prefix to place before all assertion messages. Used by make_assertion().
local assertion_message_prefix  = "Assert failed: expected "

--- The default assertions.
-- These are the assertions built into telescope. You can override them or
-- create your own custom assertions using <tt>make_assertion</tt>.
-- <ul>
-- <tt><li>assert_blank(a)</tt> - true if a is nil, or the empty string</li>
-- <tt><li>assert_empty(a)</tt> - true if a is an empty table</li>
-- <tt><li>assert_equal(a, b)</tt> - true if a == b</li>
-- <tt><li>assert_error(f)</tt> - true if function f produces an error</li>
-- <tt><li>assert_false(a)</tt> - true if a is false</li>
-- <tt><li>assert_greater_than(a, b)</tt> - true if a > b</li>
-- <tt><li>assert_gte(a, b)</tt> - true if a >= b</li>
-- <tt><li>assert_less_than(a, b)</tt> - true if a < b</li>
-- <tt><li>assert_lte(a, b)</tt> - true if a <= b</li>
-- <tt><li>assert_match(a, b)</tt> - true if b is a string that matches pattern a</li>
-- <tt><li>assert_nil(a)</tt> - true if a is nil</li>
-- <tt><li>assert_true(a)</tt> - true if a is true</li>
-- <tt><li>assert_type(a, b)</tt> - true if a is of type b</li>
-- <tt><li>assert_not_blank(a)</tt>  - true if a is not nil and a is not the empty string</li>
-- <tt><li>assert_not_empty(a)</tt> - true if a is a table, and a is not empty</li>
-- <tt><li>assert_not_equal(a, b)</tt> - true if a ~= b</li>
-- <tt><li>assert_not_error(f)</tt> - true if function f does not produce an error</li>
-- <tt><li>assert_not_false(a)</tt> - true if a is not false</li>
-- <tt><li>assert_not_greater_than(a, b)</tt> - true if not (a > b)</li>
-- <tt><li>assert_not_gte(a, b)</tt> - true if not (a >= b)</li>
-- <tt><li>assert_not_less_than(a, b)</tt> - true if not (a < b)</li>
-- <tt><li>assert_not_lte(a, b)</tt> - true if not (a <= b)</li>
-- <tt><li>assert_not_match(a, b)</tt> - true if the string b does not match the pattern a</li>
-- <tt><li>assert_not_nil(a)</tt> - true if a is not nil</li>
-- <tt><li>assert_not_true(a)</tt> - true if a is not true</li>
-- <tt><li>assert_not_type(a, b)</tt> - true if a is not of type b</li>
-- </ul>
-- @see make_assertion
-- @name assertions
-- @class table
local assertions = {}

--- Create a custom assertion.
-- This creates an assertion along with a corresponding negative assertion. It
-- is used internally by telescope to create the default assertions.
-- @param name The base name of the assertion.
-- <p>
-- The name will be used as the basis of the positive and negative assertions;
-- i.e., the name <tt>equal</tt> would be used to create the assertions
-- <tt>assert_equal</tt> and <tt>assert_not_equal</tt>.
-- </p>
-- @param message The base message that will be shown.
-- <p>
-- The assertion message is what is shown when the assertion fails.  It will be
-- prefixed with the string in <tt>telescope.assertion_message_prefix</tt>.
-- The variables passed to <tt>telescope.make_assertion</tt> are interpolated
-- in the message string using <tt>string.format</tt>.  When creating the
-- inverse assertion, the message is reused, with <tt>" to be "</tt> replaced
-- by <tt>" not to be "</tt>. Hence a recommended format is something like:
-- <tt>"%s to be similar to %s"</tt>.
-- </p>
-- @param func The assertion function itself.
-- <p>
-- The assertion function can have any number of arguments.
-- </p>
-- @usage <tt>make_assertion("equal", "%s to be equal to %s", function(a, b)
-- return a == b end)</tt>
-- @function make_assertion
local function make_assertion(name, message, func)
  local num_vars = 0
  -- if the last vararg ends up nil, we'll need to pad the table with nils so
  -- that string.format gets the number of args it expects
  local format_message
  if type(message) == "function" then
    format_message = message
  else
    for _, _ in message:gmatch("%%s") do num_vars = num_vars + 1 end
    format_message = function(message, ...)
      local a = {}
      local args = {...}
      local nargs = select('#', ...)
      if nargs > num_vars then
        local userErrorMessage = args[num_vars+1]
        if type(userErrorMessage) == "string" then
          return(assertion_message_prefix .. userErrorMessage)
        else
          error(string.format('assert_%s expected %d arguments but got %d', name, num_vars, #args))
        end
      end
      for i = 1, nargs do a[i] = tostring(args[i]) end
      for i = nargs+1, num_vars do a[i] = 'nil' end
      return (assertion_message_prefix .. message):format(unpack(a))
    end
  end

  assertions["assert_" .. name] = function(...)
    if assertion_callback then assertion_callback(...) end
    if not func(...) then
      error({format_message(message, ...), debug.traceback()})
    end
  end
end

--- (local) Return a table with table t's values as keys and keys as values.
-- @param t The table.
local function invert_table(t)
  local t2 = {}
  for k, v in pairs(t) do t2[v] = k end
  return t2
end

-- (local) Truncate a string "s" to length "len", optionally followed by the
-- string given in "after" if truncated; for example, truncate_string("hello
-- world", 3, "...")
-- @param s The string to truncate.
-- @param len The desired length.
-- @param after A string to append to s, if it is truncated.
local function truncate_string(s, len, after)
  if #s <= len then
    return s
  else
    local s = s:sub(1, len):gsub("%s*$", '')
    if after then return s .. after else return s end
  end
end

--- (local) Filter a table's values by function. This function iterates over a
-- table , returning only the table entries that, when passed into function f,
-- yield a truthy value.
-- @param t The table over which to iterate.
-- @param f The filter function.
local function filter(t, f)
  local a, b
  return function()
    repeat a, b = next(t, a)
      if not b then return end
      if f(a, b) then return a, b end
    until not b
  end
end

--- (local) Finds the value in the contexts table indexed with i, and returns a table
-- of i's ancestor contexts.
-- @param i The index in the <tt>contexts</tt> table to get ancestors for.
-- @param contexts The table in which to find the ancestors.
local function ancestors(i, contexts)
  if i == 0 then return end
  local a = {}
  local function func(j)
    if contexts[j].parent == 0 then return nil end
    table.insert(a, contexts[j].parent)
    func(contexts[j].parent)
  end
  func(i)
  return a
end

make_assertion("blank",        "'%s' to be blank",                         function(a) return a == '' or a == nil end)
make_assertion("empty",        "'%s' to be an empty table",                function(a) return not next(a) end)
make_assertion("equal",        "'%s' to be equal to '%s'",                 function(a, b) return a == b end)
make_assertion("error",        "result to be an error",                    function(f) return not pcall(f) end)
make_assertion("false",        "'%s' to be false",                         function(a) return a == false end)
make_assertion("greater_than", "'%s' to be greater than '%s'",             function(a, b) return a > b end)
make_assertion("gte",          "'%s' to be greater than or equal to '%s'", function(a, b) return a >= b end)
make_assertion("less_than",    "'%s' to be less than '%s'",                function(a, b) return a < b end)
make_assertion("lte",          "'%s' to be less than or equal to '%s'",    function(a, b) return a <= b end)
make_assertion("match",        "'%s' to be a match for %s",                function(a, b) return (tostring(b)):match(a) end)
make_assertion("nil",          "'%s' to be nil",                           function(a) return a == nil end)
make_assertion("true",         "'%s' to be true",                          function(a) return a == true end)
make_assertion("type",         "'%s' to be a %s",                          function(a, b) return type(a) == b end)

make_assertion("not_blank",    "'%s' not to be blank",                     function(a) return a ~= '' and a ~= nil end)
make_assertion("not_empty",    "'%s' not to be an empty table",            function(a) return not not next(a) end)
make_assertion("not_equal",    "'%s' not to be equal to '%s'",             function(a, b) return a ~= b end)
make_assertion("not_error",    "result not to be an error",                function(f) return not not pcall(f) end)
make_assertion("not_match",    "'%s' not to be a match for %s",            function(a, b) return not (tostring(b)):match(a) end)
make_assertion("not_nil",      "'%s' not to be nil",                       function(a) return a ~= nil end)
make_assertion("not_type",     "'%s' not to be a %s",                      function(a, b) return type(a) ~= b end)

--- Build a contexts table from the test file or function given in <tt>target</tt>.
-- If the optional <tt>contexts</tt> table argument is provided, then the
-- resulting contexts will be added to it.
-- <p>
-- The resulting contexts table's structure is as follows:
-- </p>
-- <code>
-- {
--   {parent = 0, name = "this is a context", context = true},
--   {parent = 1, name = "this is a nested context", context = true},
--   {parent = 2, name = "this is a test", test = function},
--   {parent = 2, name = "this is another test", test = function},
--   {parent = 0, name = "this is test outside any context", test = function},
-- }
-- </code>
-- @param contexts A optional table in which to collect the resulting contexts
-- and function.
-- @function load_contexts
local function load_contexts(target, contexts)
  local env = {}
  local current_index = 0
  local context_table = contexts or {}

  local function context_block(name, func)
    table.insert(context_table, {parent = current_index, name = name, context = true})
    local previous_index = current_index
    current_index = #context_table
    func()
    current_index = previous_index
  end

  local function test_block(name, func)
    local test_table = {name = name, parent = current_index, test = func or true}
    if current_index ~= 0 then
      test_table.context_name = context_table[current_index].name
    else
      test_table.context_name = 'top level'
    end
    table.insert(context_table, test_table)
  end

  local function before_block(func)
    context_table[current_index].before = func
  end

  local function after_block(func)
    context_table[current_index].after = func
  end

  for _, v in ipairs(after_aliases)   do env[v] = after_block end
  for _, v in ipairs(before_aliases)  do env[v] = before_block end
  for _, v in ipairs(context_aliases) do env[v] = context_block end
  for _, v in ipairs(test_aliases)    do env[v] = test_block end

  -- Set these functions in the module's meta table to allow accessing
  -- telescope's test and context functions without env tricks. This will
  -- however add tests to a context table used inside the module, so multiple
  -- test files will add tests to the same top-level context, which may or may
  -- not be desired.
  setmetatable(_M, {__index = env})

  setmetatable(env, {__index = _G})

  local func, err = type(target) == 'string' and assert(loadfile(target)) or target
  if err then error(err) end
  setfenv(func, env)()
  return context_table
end

-- in-place table reverse.
function table.reverse(t)
     local len = #t+1
     for i=1, (len-1)/2 do
          t[i], t[len-i] = t[len-i], t[i]
     end
end

--- Run all tests.
-- This function will exectute each function in the contexts table.
-- @param contexts The contexts created by <tt>load_contexts</tt>.
-- @param callbacks A table of callback functions to be invoked before or after
-- various test states.
-- <p>
-- There is a callback for each test <tt>status_code</tt>, and callbacks to run
-- before or after each test invocation regardless of outcome.
-- </p>
-- <ul>
-- <li>after - will be invoked after each test</li>
-- <li>before - will be invoked before each test</li>
-- <li>err - will be invoked after each test which results in an error</li>
-- <li>fail - will be invoked after each failing test</li>
-- <li>pass - will be invoked after each passing test</li>
-- <li>pending - will be invoked after each pending test</li>
-- <li>unassertive - will be invoked after each test which doesn't assert
-- anything</li>
-- </ul>
-- <p>
-- Callbacks can be used, for example, to drop into a debugger upon a failed
-- assertion or error, for profiling, or updating a GUI progress meter.
-- </p>
-- @param test_filter A function to filter tests that match only conditions that you specify.
-- <p>
-- For example, the folling would allow you to run only tests whose name matches a pattern:
-- </p>
-- <p>
-- <code>
-- function(t) return t.name:match("%s* lexer") end
-- </code>
-- </p>
-- @return A table of result tables. Each result table has the following
-- fields:
-- <ul>
-- <li>assertions_invoked - the number of assertions the test invoked</li>
-- <li>context            - the name of the context</li>
-- <li>message            - a table with an error message and stack trace</li>
-- <li>name               - the name of the test</li>
-- <li>status_code        - the resulting status code</li>
-- <li>status_label       - the label for the status_code</li>
-- </ul>
-- @see load_contexts
-- @see status_codes
-- @function run
local function run(contexts, callbacks, test_filter)

  local results = {}
  local status_names = invert_table(status_codes)
  local test_filter = test_filter or function(a) return a end

  -- Setup a new environment suitable for running a new test
  local function newEnv()
    local env = {}

    -- Make sure globals are accessible in the new environment
    setmetatable(env, {__index = _G})

    -- Setup all the assert functions in the new environment
    for k, v in pairs(assertions) do
      setfenv(v, env)
      env[k] = v
    end

    return env
  end

  local env = newEnv()

  local function invoke_callback(name, test)
    if not callbacks then return end
    if type(callbacks[name]) == "table" then
      for _, c in ipairs(callbacks[name]) do c(test) end
    elseif callbacks[name] then
      callbacks[name](test)
    end
  end

  local function invoke_test(func)
    local assertions_invoked = 0
    env.assertion_callback = function()
      assertions_invoked = assertions_invoked + 1
    end
    setfenv(func, env)
    local result, message = xpcall(func, debug.traceback)
    if result and assertions_invoked > 0 then
      return status_codes.pass, assertions_invoked, nil
    elseif result then
      return status_codes.unassertive, 0, nil
    elseif type(message) == "table" then
      return status_codes.fail, assertions_invoked, message
    else
      return status_codes.err, assertions_invoked, {message, debug.traceback()}
    end
  end

  for i, v in filter(contexts, function(i, v) return v.test and test_filter(v) end) do
    env = newEnv()    -- Setup a new environment for this test

    local ancestors = ancestors(i, contexts)
    local context_name = 'Top level'
    if contexts[i].parent ~= 0 then
      context_name = contexts[contexts[i].parent].name
    end
    local result = {
      assertions_invoked = 0,
      name               = contexts[i].name,
      context            = context_name,
      test               = i
    }
    table.sort(ancestors)
    -- this "before" is the test callback passed into the runner
    invoke_callback("before", result)

    -- run all the "before" blocks/functions
    for _, a in ipairs(ancestors) do
      if contexts[a].before then
        setfenv(contexts[a].before, env)
        contexts[a].before()
      end
    end

    -- check if it's a function because pending tests will just have "true"
    if type(v.test) == "function" then
      result.status_code, result.assertions_invoked, result.message = invoke_test(v.test)
      invoke_callback(status_names[result.status_code], result)
    else
      result.status_code = status_codes.pending
      invoke_callback("pending", result)
    end
    result.status_label = status_labels[result.status_code]

    -- Run all the "after" blocks/functions
    table.reverse(ancestors)
    for _, a in ipairs(ancestors) do
      if contexts[a].after then
        setfenv(contexts[a].after, env)
        contexts[a].after()
      end
    end

    invoke_callback("after", result)
    results[i] = result
  end

  return results

end

--- Return a detailed report for each context, with the status of each test.
-- @param contexts The contexts returned by <tt>load_contexts</tt>.
-- @param results The results returned by <tt>run</tt>.
-- @function test_report
local function test_report(contexts, results)

  local buffer               = {}
  local leading_space        = "  "
  local level                = 0
  local line_char            = "-"
  local previous_level       = 0
  local status_format_len    = 3
  local status_format        = "[%s]"
  local width                = 72
  local context_name_format  = "%-" .. width - status_format_len .. "s"
  local function_name_format = "%-" .. width - status_format_len .. "s"

  local function space()
    return leading_space:rep(level - 1)
  end

  local function add_divider()
    table.insert(buffer, line_char:rep(width))
  end
  add_divider()
  for i, item in ipairs(contexts) do
    local ancestors = ancestors(i, contexts)
    previous_level = level or 0
    level = #ancestors
    -- the 4 here is the length of "..." plus one space of padding
    local name = truncate_string(item.name, width - status_format_len - 4 - #ancestors, '...')
    if previous_level ~= level and level == 0 then add_divider() end
    if item.context then
      table.insert(buffer, context_name_format:format(space() .. name .. ':'))
    elseif results[i] then
      table.insert(buffer, function_name_format:format(space() .. name) ..
        status_format:format(results[i].status_label))
    end
  end
  add_divider()
  return table.concat(buffer, "\n")

end

--- Return a table of stack traces for tests which produced a failure or an error.
-- @param contexts The contexts returned by <tt>load_contexts</tt>.
-- @param results The results returned by <tt>run</tt>.
-- @function error_report
local function error_report(contexts, results)
  local buffer = {}
  for _, r in filter(results, function(i, r) return r.message end) do
    local name = contexts[r.test].name
    table.insert(buffer, name .. ":\n" .. r.message[1] .. "\n" .. r.message[2])
  end
  if #buffer > 0 then return table.concat(buffer, "\n") end
end

--- Get a one-line report and a summary table with the status counts. The
-- counts given are: total tests, assertions, passed tests, failed tests,
-- pending tests, and tests which didn't assert anything.
-- @return A report that can be printed
-- @return A table with the various counts. Its fields are:
-- <tt>assertions</tt>, <tt>errors</tt>, <tt>failed</tt>, <tt>passed</tt>,
-- <tt>pending</tt>, <tt>tests</tt>, <tt>unassertive</tt>.
-- @param contexts The contexts returned by <tt>load_contexts</tt>.
-- @param results The results returned by <tt>run</tt>.
-- @function summary_report
local function summary_report(contexts, results)
  local r = {
    assertions  = 0,
    errors      = 0,
    failed      = 0,
    passed      = 0,
    pending     = 0,
    tests       = 0,
    unassertive = 0
  }
  for _, v in pairs(results) do
    r.tests = r.tests + 1
    r.assertions = r.assertions + v.assertions_invoked
    if v.status_code == status_codes.err then r.errors = r.errors + 1
    elseif v.status_code == status_codes.fail then r.failed = r.failed + 1
    elseif v.status_code == status_codes.pass then r.passed = r.passed + 1
    elseif v.status_code == status_codes.pending then r.pending = r.pending + 1
    elseif v.status_code == status_codes.unassertive then r.unassertive = r.unassertive + 1
    end
  end
  local buffer = {}
  for _, k in ipairs({"tests", "passed", "assertions", "failed", "errors", "unassertive", "pending"}) do
    local number = r[k]
    local label = k
    if number == 1 then
      label = label:gsub("s$", "")
    end
    table.insert(buffer, ("%d %s"):format(number, label))
  end
  return table.concat(buffer, " "), r
end

_M.after_aliases            = after_aliases
_M.make_assertion           = make_assertion
_M.assertion_message_prefix = assertion_message_prefix
_M.before_aliases           = before_aliases
_M.context_aliases          = context_aliases
_M.error_report             = error_report
_M.load_contexts            = load_contexts
_M.run                      = run
_M.test_report              = test_report
_M.status_codes             = status_codes
_M.status_labels            = status_labels
_M.summary_report           = summary_report
_M.test_aliases             = test_aliases
_M.version                  = _VERSION
_M._VERSION                 = _VERSION

return _M