local Path = require("plenary.path")

local data_path = vim.fn.stdpath("data")
local full_data_path = string.format("%s/harpoon.json", data_path)

---@param data any
local function write_data(data)
    Path:new(full_data_path):write(vim.json.encode(data), "w")
end

local M = {}

function M.__dangerously_clear_data()
    write_data({})
end

function M.info()
    return {
        data_path = data_path,
        full_data_path = full_data_path,
    }
end

function M.set_data_path(path)
    full_data_path = path
end

local function has_keys(t)

    -- luacheck: ignore 512
    for _ in pairs(t) do
        return true
    end

    return false
end

--- @alias HarpoonRawData {[string]: {[string]: string[]}}

--- @class HarpoonData
--- @field seen {[string]: {[string]: boolean}}
--- @field _data HarpoonRawData
--- @field has_error boolean
local Data = {}

-- 1. load the data
-- 2. keep track of the lists requested
-- 3. sync save

Data.__index = Data

---@return HarpoonRawData
local function read_data()
    local path = Path:new(full_data_path)
    local exists = path:exists()

    if not exists then
        write_data({})
    end

    local out_data = path:read()
    local data = vim.json.decode(out_data)
    return data
end

---@return HarpoonData
function Data:new()
    local ok, data = pcall(read_data)

    return setmetatable({
        _data = data,
        has_error = not ok,
        seen = {},
    }, self)
end

---@param key string
---@param name string
---@return string[]
function Data:_get_data(key, name)
    if not self._data[key] then
        self._data[key] = {}
    end

    return self._data[key][name] or {}
end

---@param key string
---@param name string
---@return string[]
function Data:data(key, name)
    if self.has_error then
        error(
            "Harpoon: there was an error reading the data file, cannot read data"
        )
    end

    if not self.seen[key] then
        self.seen[key] = {}
    end

    self.seen[key][name] = true

    return self:_get_data(key, name)
end

---@param name string
---@param values string[]
function Data:update(key, name, values)
    if self.has_error then
        error(
            "Harpoon: there was an error reading the data file, cannot update"
        )
    end
    self:_get_data(key, name)
    self._data[key][name] = values
end

function Data:sync()
    if self.has_error then
        return
    end

    if not has_keys(self.seen) then
        return
    end

    local ok, data = pcall(read_data)
    if not ok then
        error("Harpoon: unable to sync data, error reading data file")
    end

    for k, v in pairs(self._data) do
        data[k] = v
    end

    ok = pcall(write_data, data)

    if ok then
        self.seen = {}
    end
end

M.Data = Data

return M