local util   = require 'utility'
local define = require 'proto.define'
local timer  = require 'timer'

---@alias config.source '"client"'|'"path"'|'"local"'

---@class config.unit
---@field caller function
local mt = {}
mt.__index = mt

function mt:__call(...)
    self:caller(...)
    return self
end

function mt:__shr(default)
    self.default = default
    return self
end

local units = {}

local function register(name, default, checker, loader, caller)
    units[name] = {
        default = default,
        checker = checker,
        loader  = loader,
        caller  = caller,
    }
end

local Type = setmetatable({}, { __index = function (_, name)
    local unit = {}
    for k, v in pairs(units[name]) do
        unit[k] = v
    end
    return setmetatable(unit, mt)
end })

register('Boolean', false, function (self, v)
    return type(v) == 'boolean'
end, function (self, v)
    return v
end)

register('Integer', 0, function (self, v)
    return type(v) == 'number'
end,function (self, v)
    return math.floor(v)
end)

register('String', '', function (self, v)
    return type(v) == 'string'
end, function (self, v)
    return tostring(v)
end)

register('Nil', nil, function (self, v)
    return type(v) == 'nil'
end, function (self, v)
    return nil
end)

register('Array', {}, function (self, value)
    return type(value) == 'table'
end, function (self, value)
    local t = {}
    for _, v in ipairs(value) do
        if self.sub:checker(v) then
            t[#t+1] = self.sub:loader(v)
        end
    end
    return t
end, function (self, sub)
    self.sub = sub
end)

register('Hash', {}, function (self, value)
    if type(value) == 'table' then
        if #value == 0 then
            for k, v in pairs(value) do
                if not self.subkey:checker(k)
                or not self.subvalue:checker(v) then
                    return false
                end
            end
        else
            if not self.subvalue:checker(true) then
                return false
            end
            for _, v in ipairs(value) do
                if not self.subkey:checker(v) then
                    return false
                end
            end
        end
        return true
    end
    if type(value) == 'string' then
        return  self.subkey:checker('')
            and self.subvalue:checker(true)
    end
end, function (self, value)
    if type(value) == 'table' then
        local t = {}
        if #value == 0 then
            for k, v in pairs(value) do
                t[k] = v
            end
        else
            for _, k in pairs(value) do
                t[k] = true
            end
        end
        return t
    end
    if type(value) == 'string' then
        local t = {}
        for s in value:gmatch('[^'..self.sep..']+') do
            t[s] = true
        end
        return t
    end
end, function (self, subkey, subvalue, sep)
    self.subkey   = subkey
    self.subvalue = subvalue
    self.sep      = sep
end)

register('Or', {}, function (self, value)
    for _, sub in ipairs(self.subs) do
        if sub:checker(value) then
            return true
        end
    end
    return false
end, function (self, value)
    for _, sub in ipairs(self.subs) do
        if sub:checker(value) then
            return sub:loader(value)
        end
    end
end, function (self, ...)
    self.subs = {...}
end)

local Template = {
    ['Lua.runtime.version']                 = Type.String >> 'Lua 5.4',
    ['Lua.runtime.path']                    = Type.Array(Type.String) >> {
                                                "?.lua",
                                                "?/init.lua",
                                            },
    ['Lua.runtime.pathStrict']              = Type.Boolean >> false,
    ['Lua.runtime.special']                 = Type.Hash(Type.String, Type.String),
    ['Lua.runtime.meta']                    = Type.String >> '${version} ${language} ${encoding}',
    ['Lua.runtime.unicodeName']             = Type.Boolean,
    ['Lua.runtime.nonstandardSymbol']       = Type.Hash(Type.String, Type.Boolean, ';'),
    ['Lua.runtime.plugin']                  = Type.String,
    ['Lua.runtime.fileEncoding']            = Type.String >> 'utf8',
    ['Lua.runtime.builtin']                 = Type.Hash(Type.String, Type.String),
    ['Lua.diagnostics.enable']              = Type.Boolean >> true,
    ['Lua.diagnostics.globals']             = Type.Hash(Type.String, Type.Boolean, ';'),
    ['Lua.diagnostics.disable']             = Type.Hash(Type.String, Type.Boolean, ';'),
    ['Lua.diagnostics.severity']            = Type.Hash(Type.String, Type.String)
                                            >> util.deepCopy(define.DiagnosticDefaultSeverity),
    ['Lua.diagnostics.neededFileStatus']    = Type.Hash(Type.String, Type.String)
                                            >> util.deepCopy(define.DiagnosticDefaultNeededFileStatus),
    ['Lua.diagnostics.workspaceDelay']      = Type.Integer >> 0,
    ['Lua.diagnostics.workspaceRate']       = Type.Integer >> 100,
    ['Lua.diagnostics.libraryFiles']        = Type.String  >> 'Opened',
    ['Lua.diagnostics.ignoredFiles']        = Type.String  >> 'Opened',
    ['Lua.workspace.ignoreDir']             = Type.Array(Type.String),
    ['Lua.workspace.ignoreSubmodules']      = Type.Boolean >> true,
    ['Lua.workspace.useGitIgnore']          = Type.Boolean >> true,
    ['Lua.workspace.maxPreload']            = Type.Integer >> 1000,
    ['Lua.workspace.preloadFileSize']       = Type.Integer >> 100,
    ['Lua.workspace.library']               = Type.Hash(Type.String, Type.Boolean, ';'),
    ['Lua.workspace.checkThirdParty']       = Type.Boolean >> true,
    ['Lua.workspace.userThirdParty']        = Type.Array(Type.String),
    ['Lua.completion.enable']               = Type.Boolean >> true,
    ['Lua.completion.callSnippet']          = Type.String  >> 'Disable',
    ['Lua.completion.keywordSnippet']       = Type.String  >> 'Replace',
    ['Lua.completion.displayContext']       = Type.Integer >> 0,
    ['Lua.completion.workspaceWord']        = Type.Boolean >> true,
    ['Lua.completion.showWord']             = Type.String  >> 'Fallback',
    ['Lua.completion.autoRequire']          = Type.Boolean >> true,
    ['Lua.completion.showParams']           = Type.Boolean >> true,
    ['Lua.completion.requireSeparator']     = Type.String  >> '.',
    ['Lua.completion.postfix']              = Type.String  >> '@',
    ['Lua.signatureHelp.enable']            = Type.Boolean >> true,
    ['Lua.hover.enable']                    = Type.Boolean >> true,
    ['Lua.hover.viewString']                = Type.Boolean >> true,
    ['Lua.hover.viewStringMax']             = Type.Integer >> 1000,
    ['Lua.hover.viewNumber']                = Type.Boolean >> true,
    ['Lua.hover.previewFields']             = Type.Integer >> 20,
    ['Lua.hover.enumsLimit']                = Type.Integer >> 5,
    ['Lua.color.mode']                      = Type.String  >> 'Semantic',
    ['Lua.hint.enable']                     = Type.Boolean >> false,
    ['Lua.hint.paramType']                  = Type.Boolean >> true,
    ['Lua.hint.setType']                    = Type.Boolean >> false,
    ['Lua.hint.paramName']                  = Type.String  >> 'All',
    ['Lua.hint.await']                      = Type.Boolean >> true,
    ['Lua.window.statusBar']                = Type.Boolean >> true,
    ['Lua.window.progressBar']              = Type.Boolean >> true,
    ['Lua.IntelliSense.traceLocalSet']      = Type.Boolean >> false,
    ['Lua.IntelliSense.traceReturn']        = Type.Boolean >> false,
    ['Lua.IntelliSense.traceBeSetted']      = Type.Boolean >> false,
    ['Lua.IntelliSense.traceFieldInject']   = Type.Boolean >> false,
    ['Lua.telemetry.enable']                = Type.Or(Type.Boolean >> false, Type.Nil),
    ['files.associations']                  = Type.Hash(Type.String, Type.String),
    ['files.exclude']                       = Type.Hash(Type.String, Type.Boolean),
    ['editor.semanticHighlighting.enabled'] = Type.Or(Type.Boolean, Type.String),
    ['editor.acceptSuggestionOnEnter']      = Type.String  >> 'on',
}

local config    = {}
local rawConfig = {}

---@class config.api
local m = {}
m.watchList = {}

local function update(key, value, raw)
    local oldValue = config[key]
    config[key]    = value
    rawConfig[key] = raw
    m.event(key, value, oldValue)
end

function m.set(key, value)
    local unit = Template[key]
    if not unit then
        return false
    end
    if util.equal(rawConfig[key], value) then
        return false
    end
    if unit:checker(value) then
        update(key, unit:loader(value), value)
    else
        update(key, unit.default, unit.default)
    end
    return true
end

function m.add(key, value)
    local unit = Template[key]
    if not unit then
        return false
    end
    local list = rawConfig[key]
    if type(list) ~= 'table' then
        return false
    end
    local copyed = {}
    for i, v in ipairs(list) do
        if util.equal(v, value) then
            return false
        end
        copyed[i] = v
    end
    copyed[#copyed+1] = value
    if unit:checker(copyed) then
        update(key, unit:loader(copyed), copyed)
    end
    return true
end

function m.prop(key, prop, value)
    local unit = Template[key]
    if not unit then
        return false
    end
    local map = rawConfig[key]
    if type(map) ~= 'table' then
        return false
    end
    if util.equal(map[prop], value) then
        return false
    end
    local copyed = {}
    for k, v in pairs(map) do
        copyed[k] = v
    end
    copyed[prop] = value
    if unit:checker(copyed) then
        update(key, unit:loader(copyed), copyed)
    end
    return true
end

function m.get(key)
    return config[key]
end

function m.getRaw(key)
   return rawConfig[key]
end

function m.dump()
    local dump = {}

    local function expand(parent, key, value)
        local left, right = key:match '([^%.]+)%.(.+)'
        if left then
            if not parent[left] then
                parent[left] = {}
            end
            expand(parent[left], right, value)
        else
            parent[key] = value
        end
    end

    for key, value in pairs(config) do
        expand(dump, key, value)
    end

    return dump
end

function m.update(new, null)
    local function expand(t, left)
        for key, value in pairs(t) do
            local fullKey = key
            if left then
                fullKey = left .. '.' .. key
            end
            if value == null then
                value = nil
            end
            if Template[fullKey] then
                m.set(fullKey, value)
            elseif Template['Lua.' .. fullKey] then
                m.set('Lua.' .. fullKey, value)
            elseif type(value) == 'table' then
                expand(value, fullKey)
            end
        end
    end

    expand(new)
end

---@param callback fun(key: string, value: any, oldValue: any)
function m.watch(callback)
    m.watchList[#m.watchList+1] = callback
end

function m.event(key, value, oldValue)
    if not m.delay then
        m.delay = {}
        timer.wait(0, function ()
            local delay = m.delay
            m.delay = nil
            for _, info in ipairs(delay) do
                for _, callback in ipairs(m.watchList) do
                    callback(info.key, info.value, info.oldValue)
                end
            end
        end)
    end
    m.delay[#m.delay+1] = {
        key      = key,
        value    = value,
        oldValue = oldValue,
    }
end

function m.init()
    if m.inited then
        return
    end
    m.inited = true
    for key, unit in pairs(Template) do
        m.set(key, unit.default)
    end
end

return m