--!A cross-platform build utility based on Lua
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Copyright (C) 2015-present, Xmake Open Source Community.
--
-- @author      ruki
-- @file        linker.lua
--

-- define module
local linker = linker or {}

-- load modules
local io        = require("base/io")
local path      = require("base/path")
local utils     = require("base/utils")
local table     = require("base/table")
local string    = require("base/string")
local option    = require("base/option")
local profiler  = require("base/profiler")
local config    = require("project/config")
local sandbox   = require("sandbox/sandbox")
local language  = require("language/language")
local platform  = require("platform/platform")
local tool      = require("tool/tool")
local builder   = require("tool/builder")
local compiler  = require("tool/compiler")

-- add flags from the toolchains
function linker:_add_flags_from_toolchains(flags, targetkind, target)

    -- attempt to add special lanugage flags first for target kind, e.g. binary.go.gcldflags, static.dcarflags
    if targetkind then
        local toolkind = self:kind()
        local toolname = self:name()
        if target and target.toolconfig then
            for _, flagkind in ipairs(self:_flagkinds()) do
                local toolflags = target:toolconfig(targetkind .. '.' .. toolname .. '.' .. toolkind .. 'flags') or target:toolconfig(targetkind .. '.' .. toolname .. '.' .. flagkind)
                table.join2(flags, toolflags or target:toolconfig(targetkind .. '.' .. toolkind .. 'flags') or target:toolconfig(targetkind .. '.' .. flagkind))
            end
        else
            for _, flagkind in ipairs(self:_flagkinds()) do
                local toolflags = platform.toolconfig(targetkind .. '.' .. toolname .. '.' .. toolkind .. 'flags') or platform.toolconfig(targetkind .. '.' .. toolname .. '.' .. flagkind)
                table.join2(flags, toolflags or platform.toolconfig(targetkind .. '.' .. toolkind .. 'flags') or platform.toolconfig(targetkind .. '.' .. flagkind))
            end
        end
    end
end

-- add flags from the linker
function linker:_add_flags_from_linker(flags)
    local toolkind = self:kind()
    for _, flagkind in ipairs(self:_flagkinds()) do
        -- attempt to add special lanugage flags first, e.g. gcldflags, dcarflags
        table.join2(flags, self:get(toolkind .. "flags") or self:get(flagkind))
    end
end

-- load tool
function linker._load_tool(targetkind, sourcekinds, target)

    -- get the linker infos
    local linkerinfos, errors = language.linkerinfos_of(targetkind, sourcekinds)
    if not linkerinfos then
        return nil, errors
    end

    -- select the linker
    local linkerinfo = nil
    local linkertool = nil
    local firsterror = nil
    for _, _linkerinfo in ipairs(linkerinfos) do

        -- get program from target
        local program, toolname, toolchain_info
        if target and target.tool then
            program, toolname, toolchain_info = target:tool(_linkerinfo.linkerkind)
        end

        -- is host?
        local is_host
        if target and target.is_host then
            is_host = target:is_host()
        end

        -- load the linker tool from the linker kind (with cache)
        linkertool, errors = tool.load(_linkerinfo.linkerkind, {
            host = is_host,
            program = program,
            toolname = toolname,
            toolchain_info = toolchain_info})
        if linkertool then
            linkerinfo = _linkerinfo
            linkerinfo.program = program
            break
        else
            firsterror = firsterror or errors
        end
    end
    if not linkerinfo then
        return nil, firsterror
    end
    return linkertool, linkerinfo
end

-- load the linker from the given target kind
function linker.load(targetkind, sourcekinds, target)
    assert(sourcekinds)

    -- wrap sourcekinds first
    sourcekinds = table.wrap(sourcekinds)
    if #sourcekinds == 0 then
        -- we need to detect the sourcekinds of all deps if the current target has not any source files
        for _, dep in ipairs(target:orderdeps()) do
            table.join2(sourcekinds, dep:sourcekinds())
        end
        if #sourcekinds > 0 then
            sourcekinds = table.unique(sourcekinds)
        end
    end

    -- load linker tool first, we need to get the correct plat/arch
    -- @NOTE We cannot cache the tool, otherwise it may cause duplicate toolchain flags to be added
    local linkertool, linkerinfo_or_errors = linker._load_tool(targetkind, sourcekinds, target)
    if not linkertool then
        return nil, linkerinfo_or_errors
    end

    -- get linker info
    local linkerinfo = linkerinfo_or_errors

    -- init cache key
    local plat = linkertool:plat() or config.plat() or os.host()
    local arch = linkertool:arch() or config.arch() or os.arch()
    local cachekey = targetkind .. "_" .. linkerinfo.linkerkind .. (linkerinfo.program or "") .. plat .. arch
    cachekey = cachekey .. table.concat(sourcekinds, "") -- @see https://github.com/xmake-io/xmake/issues/5360
    if target then
        cachekey = cachekey .. tostring(target)
    end

    -- get it directly from cache dirst
    builder._INSTANCES = builder._INSTANCES or {}
    local instance = builder._INSTANCES[cachekey]
    if not instance then

        -- new instance
        instance = table.inherit(linker, builder)

        -- save linker tool
        instance._TOOL = linkertool

        -- load the name flags of archiver
        local nameflags = {}
        local nameflags_exists = {}
        for _, sourcekind in ipairs(sourcekinds) do

            -- load language
            local result, errors = language.load_sk(sourcekind)
            if not result then
                return nil, errors
            end

            -- merge name flags
            for _, flaginfo in ipairs(table.wrap(result:nameflags()[targetkind])) do
                local key = flaginfo[1] .. flaginfo[2]
                if not nameflags_exists[key] then
                    table.insert(nameflags, flaginfo)
                    nameflags_exists[key] = flaginfo
                end
            end
        end
        instance._NAMEFLAGS = nameflags

        -- init target (optional)
        instance._TARGET = target

        -- init target kind
        instance._TARGETKIND = targetkind

        -- init flag kinds
        instance._FLAGKINDS = {linkerinfo.linkerflag}

        -- add toolchains flags to the linker tool
        -- add special lanugage flags first, e.g. go.gcldflags or gcc.ldflags or gcldflags or ldflags
        local toolkind = linkertool:kind()
        local toolname = linkertool:name()
        if target and target.toolconfig then
            for _, flagkind in ipairs(instance:_flagkinds()) do
                linkertool:add(toolkind .. 'flags', target:toolconfig(toolname .. '.' .. toolkind .. 'flags') or target:toolconfig(toolkind .. 'flags'))
                linkertool:add(flagkind, target:toolconfig(toolname .. '.' .. flagkind) or target:toolconfig(flagkind))
            end
        else
            for _, flagkind in ipairs(instance:_flagkinds()) do
                linkertool:add(toolkind .. 'flags', platform.toolconfig(toolname .. '.' .. toolkind .. 'flags') or platform.toolconfig(toolkind .. 'flags'))
                linkertool:add(flagkind, platform.toolconfig(toolname .. '.' .. flagkind) or platform.toolconfig(flagkind))
            end
        end

        -- @note we can't call _load_once before caching the instance,
        -- it may call has_flags to trigger the concurrent scheduling.
        --
        -- this will result in more compiler/linker instances being created at the same time,
        -- and they will access the same tool instance at the same time.
        --
        -- @see https://github.com/xmake-io/xmake/issues/3429
        builder._INSTANCES[cachekey] = instance
    end

    -- we need to load it at the end because in tool.load().
    -- because we may need to call has_flags, which requires the full platform toolchain flags
    local ok, errors = instance:_tool():_load_once()
    if not ok then
        return nil, errors
    end
    return instance
end

-- link the target file
function linker:link(objectfiles, targetfile, opt)
    opt = opt or {}
    local linkflags = opt.linkflags or self:linkflags(opt)
    profiler:enter(self:name(), "link", targetfile)
    local ok, errors = sandbox.load(self:_tool().link, self:_tool(),
        table.wrap(objectfiles), self:_targetkind(), targetfile, linkflags,
        table.join(opt, {target = self:target()}))
    profiler:leave(self:name(), "link", targetfile)
    return ok, errors
end

-- get the link arguments list
function linker:linkargv(objectfiles, targetfile, opt)
    opt = opt or {}
    return self:_tool():linkargv(table.wrap(objectfiles),
        self:_targetkind(), targetfile, opt.linkflags or self:linkflags(opt),
        table.join(opt, {target = self:target()}))
end

-- get the link command
function linker:linkcmd(objectfiles, targetfile, opt)
    return os.args(table.join(self:linkargv(objectfiles, targetfile, opt)))
end

-- get the link flags
--
-- @param opt   the argument options (contain all the linker attributes of target),
--              e.g. {target = ..., targetkind = "static", configs = {ldflags = "", links = "", linkdirs = "", ...}}
--
function linker:linkflags(opt)
    opt = opt or {}

    -- get target
    local target = opt.target or self:target()
    local targetkind = opt.targetkind
    if not targetkind and target and target:type() == "target" then
        targetkind = target:kind()
    end

    -- add flags from linker/toolchains
    --
    -- we need to add toolchain flags at the beginning to allow users to override them.
    -- but includedirs/links/syslinks/linkdirs will still be placed last, they are in the order defined in languages/xmake.lua
    --
    -- @see https://github.com/xmake-io/xmake/issues/978
    --
    local flags = {}
    self:_add_flags_from_linker(flags)
    self:_add_flags_from_toolchains(flags, targetkind, target)

    -- add flags from target
    self:_add_flags_from_target(flags, target)

    -- add flags from argument
    local configs = opt.configs or opt.config
    if configs then
        self:_add_flags_from_argument(flags, target, configs)
    end

    -- add flags from user configuration
    self:_add_flags_from_config(flags)

    -- preprocess flags
    return self:_preprocess_flags(flags)
end

-- return module
return linker