local _ENV = mkmodule('utils')

local df = df

-- Comparator function
function compare(a,b)
    if a < b then
        return -1
    elseif a > b then
        return 1
    else
        return 0
    end
end

-- Sort strings; compare empty last
function compare_name(a,b)
    if a == '' then
        if b == '' then
            return 0
        else
            return 1
        end
    elseif b == '' then
        return -1
    else
        return compare(a,b)
    end
end

-- Make a field comparator
function compare_field(field,cmp)
    cmp = cmp or compare
    if field then
        return function (a,b)
            return cmp(a[field],b[field])
        end
    else
        return cmp
    end
end

-- Make a comparator of field vs key
function compare_field_key(field,cmp)
    cmp = cmp or compare
    if field then
        return function (a,b)
            return cmp(a[field],b)
        end
    else
        return cmp
    end
end

function is_container(obj)
    return df.isvalid(obj) == 'ref' and obj._kind == 'container'
end

-- Make a sequence of numbers in 1..size
function make_index_sequence(size)
    local index = {}
    for i=1,size do
        index[i] = i
    end
    return index
end

--[[
    Sort items in data according to ordering.

    Each ordering spec is a table with possible fields:

    * key = function(value)
        Computes comparison key from a data value. Not called on nil.
    * key_table = function(data)
        Computes a key table from the data table in one go.
    * compare = function(a,b)
        Comparison function. Defaults to compare above.
        Called on non-nil keys; nil sorts last.
    * nil_first
        If true, nil keys are sorted first instead of last.
    * reverse
        If true, sort non-nil keys in descending order.

    Returns a table of integer indices into data.
--]]
function make_sort_order(data,ordering)
    -- Compute sort keys and comparators
    local keys = {}
    local cmps = {}
    local size = data.n or #data

    for i=1,#ordering do
        local order = ordering[i]

        if order.key_table then
            keys[i] = order.key_table(data)
        elseif order.key then
            local kt = {}
            local kf = order.key
            for j=1,size do
                if data[j] == nil then
                    kt[j] = nil
                else
                    kt[j] = kf(data[j])
                end
            end
            keys[i] = kt
        else
            keys[i] = data
        end

        cmps[i] = order.compare or compare
    end

    -- Make an order table
    local index = make_index_sequence(size)

    -- Sort the ordering table
    table.sort(index, function(ia,ib)
        for i=1,#keys do
            local ka = keys[i][ia]
            local kb = keys[i][ib]

            -- Sort nil keys to the end
            if ka == nil then
                if kb ~= nil then
                    return ordering[i].nil_first
                end
            elseif kb == nil then
                return not ordering[i].nil_first
            else
                local cmpv = cmps[i](ka,kb)
                if ordering[i].reverse then
                    cmpv = -cmpv
                end
                if cmpv < 0 then
                    return true
                elseif cmpv > 0 then
                    return false
                end
            end
        end
        return ia < ib -- this should ensure stable sort
    end)

    return index
end

--[[
    Recursively assign data into a table.
--]]
function assign(tgt,src)
    if df.isvalid(tgt) == 'ref' then
        df.assign(tgt, src)
    elseif type(tgt) == 'table' then
        for k,v in pairs(src) do
            if type(v) == 'table' then
                local cv = tgt[k]
                if cv == nil then
                    cv = {}
                    tgt[k] = cv
                end
                assign(cv, v)
            else
                tgt[k] = v
            end
        end
    else
        error('Invalid assign target type: '..tostring(tgt))
    end
    return tgt
end

local function copy_field(obj,k,v,deep)
    if v == nil then
        return NULL
    end
    if deep then
        local field = obj:_field(k)
        if field == v then
            return clone(v,deep)
        end
    end
    return v
end

-- Copy the object as lua data structures.
function clone(obj,deep)
    if type(obj) == 'table' then
        if deep then
            return assign({},obj)
        else
            return copyall(obj)
        end
    elseif df.isvalid(obj) == 'ref' then
        local kind = obj._kind
        if kind == 'primitive' then
            return obj.value
        elseif kind == 'bitfield' then
            local rv = {}
            for k,v in pairs(obj) do
                rv[k] = v
            end
            return rv
        elseif kind == 'container' then
            local rv = {}
            for k,v in ipairs(obj) do
                rv[k+1] = copy_field(obj,k,v,deep)
            end
            return rv
        else -- struct
            local rv = {}
            for k,v in pairs(obj) do
                rv[k] = copy_field(obj,k,v,deep)
            end
            return rv
        end
    else
        return obj
    end
end

local function get_default(default,key,base)
    if type(default) == 'table' then
        local dv = default[key]
        if dv == nil then
            dv = default._default
        end
        if dv == nil then
            dv = base
        end
        return dv
    else
        return default
    end
end

-- Copy the object as lua data structures, skipping values matching defaults.
function clone_with_default(obj,default,force)
    local rv = nil
    local function setrv(k,v)
        if v ~= nil then
            if rv == nil then
                rv = {}
            end
            rv[k] = v
        end
    end
    if default == nil then
        return nil
    elseif type(obj) == 'table' then
        for k,v in pairs(obj) do
            setrv(k, clone_with_default(v, get_default(default,k)))
        end
    elseif df.isvalid(obj) == 'ref' then
        local kind = obj._kind
        if kind == 'primitive' then
            return clone_with_default(obj.value,default,force)
        elseif kind == 'bitfield' then
            for k,v in pairs(obj) do
                setrv(k, clone_with_default(v, get_default(default,k,false)))
            end
        elseif kind == 'container' then
            for k,v in ipairs(obj) do
                setrv(k+1, clone_with_default(v, default, true))
            end
        else -- struct
            for k,v in pairs(obj) do
                setrv(k, clone_with_default(v, get_default(default,k)))
            end
        end
    elseif obj == default and not force then
        return nil
    elseif obj == nil then
        return NULL
    else
        return obj
    end
    if force and rv == nil then
        rv = {}
    end
    return rv
end

-- Sort a vector or lua table
function sort_vector(vector,field,cmp)
    local fcmp = compare_field(field,cmp)
    local scmp = function(a,b)
        return fcmp(a,b) < 0
    end
    if df.isvalid(vector) then
        if vector._kind ~= 'container' then
            error('Container expected: '..tostring(vector))
        end
        local items = clone(vector, true)
        table.sort(items, scmp)
        vector:assign(items)
    else
        table.sort(vector, scmp)
    end
    return vector
end

-- Binary search in a vector or lua table
function binsearch(vector,key,field,cmp,min,max)
    if not(min and max) then
        if df.isvalid(vector) then
            min = -1
            max = #vector
        else
            min = 0
            max = #vector+1
        end
    end
    local mf = math.floor
    local fcmp = compare_field_key(field,cmp)
    while true do
        local mid = mf((min+max)/2)
        if mid <= min then
            return nil, false, max
        end
        local item = vector[mid]
        local cv = fcmp(item, key)
        if cv == 0 then
            return item, true, mid
        elseif cv < 0 then
            min = mid
        else
            max = mid
        end
    end
end

-- Binary search and insert
function insert_sorted(vector,item,field,cmp)
    local key = item
    if field and item then
        key = item[field]
    end
    local cur,found,pos = binsearch(vector,key,field,cmp)
    if found then
        return false,cur,pos
    else
        if df.isvalid(vector) then
            vector:insert(pos, item)
        else
            table.insert(vector, pos, item)
        end
        return true,vector[pos],pos
    end
end

-- Binary search, then insert or overwrite
function insert_or_update(vector,item,field,cmp)
    local added,cur,pos = insert_sorted(vector,item,field,cmp)
    if not added then
        vector[pos] = item
        cur = vector[pos]
    end
    return added,cur,pos
end

-- Ask a yes-no question
function prompt_yes_no(msg,default)
    local prompt = msg
    if default == nil then
        prompt = prompt..' (y/n): '
    elseif default then
        prompt = prompt..' (y/n/enter=y): '
    else
        prompt = prompt..' (y/n/enter=n): '
    end
    while true do
        local rv = dfhack.lineedit(prompt)
        if rv then
            if string.match(rv,'^[Yy]') then
                return true
            elseif string.match(rv,'^[Nn]') then
                return false
            elseif rv == '' and default ~= nil then
                return default
            end
        end
    end
end

-- Ask for input with check function
function prompt_input(prompt,check,quit_str)
    quit_str = quit_str or '~~~'
    while true do
        local rv = dfhack.lineedit(prompt)
        if rv == quit_str then
            return nil
        end
        local rtbl = table.pack(check(rv))
        if rtbl[1] then
            return table.unpack(rtbl,2,rtbl.n)
        end
    end
end

function check_number(text)
    local nv = tonumber(text)
    return nv ~= nil, nv
end

return _ENV