---@mod rest-nvim.context rest.nvim context (mainly about variables)

local dotenv = require("rest-nvim.dotenv")
local config = require("rest-nvim.config")
local logger = require("rest-nvim.logger")
local M = {}

---@class rest.Context
---global variables
---@field vars table<string,string>
---local variables
---@field lv table<string,string>
---current line number (to evaluate variable declaration sequentially)
---@field linenr number
local Context = {}
Context.__index = Context

local random = math.random
math.randomseed(os.time())

---Generate a random uuid
---@return string
local function uuid()
    local template = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"
    local s = string.gsub(template, "[xy]", function(c)
        local v = (c == "x") and random(0, 0xf) or random(8, 0xb)
        return string.format("%x", v)
    end)
    return s
end

---@type table<string,fun():string>
local rest_variables = {
    uuid = uuid,
    date = function()
        return os.date("%Y-%m-%d") --[[@as string]]
    end,
    timestamp = function()
        return tostring(os.time()) or ""
    end,
    randomInt = function()
        return tostring(math.random(0, 1000))
    end,
}

---@return rest.Context
function Context:new()
    ---@type rest.Context
    local obj = {
        __index = self,
        linenr = 0,
        vars = {},
        lv = {},
    }
    setmetatable(obj, self)
    return obj
end

---@param filepath string
function Context:load_file(filepath)
    logger.debug(("load file `%s` to context"):format(filepath))
    dotenv.load_file(filepath, function(key, value)
        self:set_global(key, value)
    end)
end

---@param key string
---@param value string
function Context:set_global(key, value)
    vim.validate({
        key = { key, "string" },
        value = { value, "string" },
    })
    self.vars[key] = value
end

---@param key string
---@param value string
function Context:set_local(key, value)
    vim.validate({
        key = { key, "string" },
        value = { value, "string" },
    })
    self.lv[key] = value
end

function Context:clear_local()
    self.lv = {}
end

---@param key string
---@return nil|fun():string
local function get_dynamic_vars(key)
    local user_variables = config.custom_dynamic_variables
    if user_variables[key] then
        return user_variables[key]
        -- TODO: remove this elseif statement in 4.0.0 release
    elseif user_variables["$" .. key] then
        return user_variables["$" .. key]
    end
    return rest_variables[key]
end

---resolves variable
---1. variables from pre-request scripts (local to each requests)
---2. in-place variables (local to each .http files)
---3. selected dotenv file (local to each .http files)
---returns empty string if variable is not set
---@param key string
---@return string value
function Context:resolve(key)
    -- find from dynamic variables
    if vim.startswith(key, "$") then
        logger.debug("resolving dynamic variable:", key)
        local var = get_dynamic_vars(key:sub(2))
        return var and var() or ""
    end
    -- find from local variable table or vim.env
    logger.debug("resolving variable:", key)
    return self.lv[key] or self.vars[key] or vim.env[key] or ""
end

M.Context = Context

return M