-- This code is derived from the SOM benchmarks, see AUTHORS.md file.
--
-- Copyright (c) 2016 Francois Perrad <francois.perrad@gadz.org>
--
-- 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 of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- 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.

--[[
    The module 'bit' is available with:
      * LuaJIT
      * LuaBitOp extension which is available for:
          * Lua 5.1
          * Lua 5.2
    The module 'bit32' is available with:
      * Lua 5.2
      * Lua 5.3 when compiled with LUA_COMPAT_5_2
    The bitwise operators are added to Lua 5.3 as new lexemes (there causes
    lexical error in older version)
--]]
local band, bxor, rshift
if _VERSION < 'Lua 5.3' then
    local bit = bit32 or require'bit'
    band = bit.band
    bxor = bit.bxor
    rshift = bit.rshift
else
    band = assert(load'--[[band]] return function (a, b) return a & b end')()
    bxor = assert(load'--[[bxor]] return function (a, b) return a ~ b end')()
    rshift = assert(load'--[[rshift]] return function (a, b) return a >> b end')()
end

local alloc_array
local ok, table_new = pcall(require, 'table.new')       -- LuaJIT 2.1 extension
if ok then
    alloc_array = function (n)
        local t = table_new(n, 1)
        t.n = n
        return t
    end
else
    alloc_array = function (n)
        local t = {}
        t.n = n
        return t
    end
end

local Vector = {_CLASS = 'Vector'} do

local floor = math.floor

function Vector.new (size)
    local obj = {
        storage   = alloc_array(size or 50),
        first_idx = 1,
        last_idx  = 1,
    }
    return setmetatable(obj, {__index = Vector})
end

function Vector.with (elem)
    local v = Vector.new(1)
    v:append(elem)
    return v
end

function Vector:at (idx)
    if idx > self.storage.n then
        return nil
    end
    return self.storage[idx]
end

function Vector:at_put (idx, val)
    if idx > self.storage.n then
        local new_n = self.storage.n
        while idx > new_n do
            new_n = new_n * 2
        end

        local new_storage = alloc_array(new_n)
        for i = 1, self.storage.n do
            new_storage[i] = self.storage[i]
        end
        self.storage = new_storage
    end
    self.storage[idx] = val

    if self.last_idx < idx + 1 then
        self.last_idx = idx + 1
    end
end

function Vector:append (elem)
    if self.last_idx > self.storage.n then
        -- Need to expand capacity first
        local new_storage = alloc_array(2 * self.storage.n)
        for i = 1, self.storage.n do
            new_storage[i] = self.storage[i]
        end
        self.storage = new_storage
    end

    self.storage[self.last_idx] = elem
    self.last_idx = self.last_idx + 1
end

function Vector:is_empty ()
    return self.last_idx == self.first_idx
end

function Vector:each (fn)
    for i = self.first_idx, self.last_idx - 1 do
        fn(self.storage[i])
    end
end

function Vector:has_some (fn)
    for i = self.first_idx, self.last_idx - 1 do
        if fn(self.storage[i]) then
            return true
        end
    end
    return false
end

function Vector:get_one (fn)
    for i = self.first_idx, self.last_idx - 1 do
        local e = self.storage[i]
        if fn(e) then
            return e
        end
    end
    return nil
end

function Vector:remove_first ()
    if self:is_empty() then
        return nil
    end

    self.first_idx = self.first_idx + 1
    return self.storage[self.first_idx - 1]
end

function Vector:remove (obj)
    local new_array = alloc_array(self:capacity())
    local new_last = 1
    local found = false

    self:each(function (it)
        if it == obj then
            found = true
        else
            new_array[new_last] = it
            new_last = new_last + 1
        end
    end)

    self.storage   = new_array
    self.last_idx  = new_last
    self.first_idx = 1
    return found
end

function Vector:remove_all ()
    self.first_idx = 1
    self.last_idx = 1
    self.storage = alloc_array(self:capacity())
end

function Vector:size ()
    return self.last_idx - self.first_idx
end

function Vector:capacity ()
    return self.storage.n
end

function Vector:sort (fn)
    -- Make the argument, block, be the criterion for ordering elements of
    -- the receiver.
    -- Sort blocks with side effects may not work right.
    if self:size() > 0 then
        self:sort_range(self.first_idx, self.last_idx - 1, fn)
    end
end

function Vector:sort_range (i, j, fn)
    assert(fn)

    -- The prefix d means the data at that index.
    local n = j + 1 - i
    if n <= 1 then
        -- Nothing to sort
        return
    end

    local storage = self.storage
    -- Sort di, dj
    local di = storage[i]
    local dj = storage[j]

    -- i.e., should di precede dj?
    if not fn(di, dj) then
        local tmp = storage[i]
        storage[i] = storage[j]
        storage[j] = tmp
        local tt = di
        di = dj
        dj = tt
    end

    -- NOTE: For DeltaBlue, this is never reached.
    if n > 2 then               -- More than two elements.
        local ij  = floor((i + j) / 2)  -- ij is the midpoint of i and j.
        local dij = storage[ij]         -- Sort di,dij,dj.  Make dij be their median.

        if fn(di, dij) then             -- i.e. should di precede dij?
            if not fn(dij, dj) then     -- i.e., should dij precede dj?
               local tmp = storage[j]
               storage[j] = storage[ij]
               storage[ij] = tmp
               dij = dj
            end
        else                            -- i.e. di should come after dij
            local tmp = storage[i]
            storage[i] = storage[ij]
            storage[ij] = tmp
            dij = di
        end

        if n > 3 then           -- More than three elements.
            -- Find k>i and l<j such that dk,dij,dl are in reverse order.
            -- Swap k and l.  Repeat this procedure until k and l pass each other.
            local k = i
            local l = j - 1

            while true do
                -- i.e. while dl succeeds dij
                while k <= l and fn(dij, storage[l]) do
                    l = l - 1
                end

                k = k + 1
                -- i.e. while dij succeeds dk
                while k <= l and fn(storage[k], dij) do
                    k = k + 1
                end

                if k > l then
                    break
                end

                local tmp = storage[k]
                storage[k] = storage[l]
                storage[l] = tmp
            end

            -- Now l < k (either 1 or 2 less), and di through dl are all
            -- less than or equal to dk through dj.  Sort those two segments.
            self:sort_range(i, l, fn)
            self:sort_range(k, j, fn)
        end
    end
end

end -- class Vector

local Set = {_CLASS = 'Set'} do

local INITIAL_SIZE = 10

function Set.new (size)
    local obj = {
        items = Vector.new(size or INITIAL_SIZE)
    }
    return setmetatable(obj, {__index = Set})
end

function Set:size ()
    return self.items:size()
end

function Set:each (fn)
    self.items:each(fn)
end

function Set:has_some (fn)
    return self.items:has_some(fn)
end

function Set:get_one (fn)
    return self.items:get_one(fn)
end

function Set:add (obj)
    if not self:contains(obj) then
        self.items:append(obj)
    end
end

function Set:remove_all ()
    self.items:remove_all()
end

function Set:collect (fn)
    local coll = Vector.new()
    self:each(function (it)
        coll:append(fn(it))
    end)
    return coll
end

function Set:contains (obj)
    return self:has_some(function (it) return it == obj end)
end

end -- class Set

local IdentitySet = {_CLASS = 'IdentitySet'} do
setmetatable(IdentitySet, {__index = Set})

function IdentitySet.new (size)
    local obj = Set.new(size)
    return setmetatable(obj, {__index = IdentitySet})
end

function IdentitySet:contains (obj)
    return self:has_some(function (it) return it == obj end)
end

end -- class IdentitySet

local Entry = {_CLASS = 'Entry'} do

function Entry.new (hash, key, value, next)
    local obj = {
        hash  = hash,
        key   = key,
        value = value,
        next  = next,
    }
    return setmetatable(obj, {__index = Entry})
end

function Entry:match (hash, key)
    return self.hash == hash and self.key == key
end

end -- class Entry

local Dictionary = {_CLASS = 'Dictionary'} do

local INITIAL_CAPACITY = 16

function Dictionary.new (size)
    local obj = {
        buckets = alloc_array(size or INITIAL_CAPACITY),
        size    = 0,
    }
    return setmetatable(obj, {__index = Dictionary})
end

function Dictionary:hash (key)
    if not key then
        return 0
    end
    local hash = key:custom_hash()
    return bxor(hash, rshift(hash, 16))
end

function Dictionary:is_empty ()
    return self.size == 0
end

function Dictionary:get_bucket_idx (hash)
    return band(self.buckets.n - 1, hash) + 1
end

function Dictionary:get_bucket (hash)
    return self.buckets[self:get_bucket_idx(hash)]
end

function Dictionary:at (key)
    local hash = self:hash(key)
    local e = self:get_bucket(hash)

    while e do
        if e:match(hash, key) then
            return e.value
        end
        e = e.next
    end
    return nil
end

function Dictionary:contains_key (key)
    local hash = self:hash(key)
    local e = self:get_bucket(hash)

    while e do
        if e.match(hash, key) then
            return true
        end
        e = e.next
    end
    return false
end

function Dictionary:at_put (key, value)
    local hash = self:hash(key)
    local i = self:get_bucket_idx(hash)
    local current = self.buckets[i]

    if not current then
        self.buckets[i] = self:new_entry(key, value, hash)
        self.size = self.size + 1
    else
        self:insert_bucket_entry(key, value, hash, current)
    end

    if self.size > self.buckets.n then
        self:resize()
    end
end

function Dictionary:new_entry (key, value, hash)
    return Entry.new(hash, key, value, nil)
end

function Dictionary:insert_bucket_entry (key, value, hash, head)
    local current = head

    while true do
        if current:match(hash, key) then
            current.value = value
            return
        end
        if not current.next then
            self.size = self.size + 1
            current.next = self:new_entry(key, value, hash)
            return
        end
        current = current.next
    end
end

function Dictionary:resize ()
    local old_storage = self.buckets
    self.buckets = alloc_array(old_storage.n * 2)
    self:transfer_entries(old_storage)
end

function Dictionary:transfer_entries (old_storage)
    local buckets = self.buckets
    for i = 1, old_storage.n do
        local current = old_storage[i]

        if current then
            old_storage[i] = nil
            if not current.next then
                local hash = band(current.hash, buckets.n - 1) + 1
                buckets[hash] = current
            else
                self:split_bucket(old_storage, i, current)
            end
        end
    end
end

function Dictionary:split_bucket (old_storage, i, head)
    local lo_head, lo_tail = nil, nil
    local hi_head, hi_tail = nil, nil
    local current = head

    while current do
        if band(current.hash, old_storage.n) == 0 then
            if not lo_tail then
               lo_head = current
            else
                lo_tail.next = current
            end
            lo_tail = current
        else
            if not hi_tail then
                hi_head = current
            else
                hi_tail.next = current
            end
            hi_tail = current
        end
       current = current.next
    end

    if lo_tail then
        lo_tail.next = nil
        self.buckets[i] = lo_head
    end
    if hi_tail then
        hi_tail.next = nil
        self.buckets[i + old_storage.n] = hi_head
    end
end

function Dictionary:remove_all ()
    self.buckets = alloc_array(self.buckets.n)
    self.size = 0
end

function Dictionary:keys ()
    local keys = Vector.new(self.size)
    local buckets = self.buckets
    for i = 1, buckets.n do
        local current = buckets[i]
        while current do
            keys:append(current.key)
            current = current.next
        end
    end
    return keys
end

function Dictionary:values ()
    local vals = Vector.new(self.size)
    local buckets = self.buckets
    for i = 1, buckets.n do
        local current = buckets[i]
        while current do
            vals:append(current.value)
            current = current.next
        end
    end
    return vals
end

end -- class Dictionary

local IdEntry = {_CLASS = 'IdEntry'} do
setmetatable(IdEntry, {__index = Entry})

function IdEntry.new (hash, key, value, next)
    local obj = Entry.new (hash, key, value, next)
    return setmetatable(obj, {__index = IdEntry})
end

function IdEntry:match (hash, key)
    return self.hash == hash and self.key == key
end

end -- class IdEntry

local IdentityDictionary = {_CLASS = 'IdentityDictionary'} do
setmetatable(IdentityDictionary, {__index = Dictionary})

function IdentityDictionary.new (size)
    local obj = Dictionary.new (size)
    return setmetatable(obj, {__index = Dictionary})
end

function IdentityDictionary:new_entry (key, value, hash)
    return IdEntry.new(hash, key, value, nil)
end

end -- class IdentityDictionary

local Random = {_CLASS = 'Random'} do

function Random.new ()
    local obj = {seed = 74755}
    return setmetatable(obj, {__index = Random})
end

function Random:next ()
  self.seed = band(((self.seed * 1309) + 13849), 65535);
  return self.seed;
end

end -- class Random

---------------------------------

local benchmark = {} do

function benchmark:inner_benchmark_loop (inner_iterations)
    for _ = 1, inner_iterations do
        if not self:verify_result(self:benchmark()) then
            return false
        end
    end
    return true
end

function benchmark:benchmark ()
    error 'subclass_responsibility'
end

function benchmark:verify_result ()
    error 'subclass_responsibility'
end

end

---------------------------------

local Element = {_CLASS = 'Element'} do

function Element.new (v)
    local obj = {val = v, next = nil}
    return setmetatable(obj, {__index = Element})
end

function Element:length ()
    if not self.next then
        return 1
    else
        return 1 + self.next:length()
    end
end

end -- class Element

local list = {} do
setmetatable(list, {__index = benchmark})

function list:benchmark ()
    local result = self:tail(self:make_list(15),
                             self:make_list(10),
                             self:make_list(6))
    return result:length()
end

function list:make_list (length)
    if length == 0 then
        return nil
    else
        local e = Element.new(length)
        e.next = self:make_list(length - 1)
        return e
    end
end

function list:is_shorter_than (x, y)
    local x_tail, y_tail = x, y
    while y_tail do
        if not x_tail then
            return true
        end
        x_tail = x_tail.next
        y_tail = y_tail.next
    end
    return false
end

function list:tail (x, y, z)
    if self:is_shorter_than(y, x) then
        return self:tail(self:tail(x.next, y, z),
                         self:tail(y.next, z, x),
                         self:tail(z.next, x, y))
    else
        return z
    end
end

function list:verify_result (result)
    return 10 == result
end

end -- object list

return function(N)
    list:inner_benchmark_loop(N)
end