local RefreshTask = require("lsp.codelens.refresh_task")
local Row = require("lsp.codelens.row")
local util = require("util")

local REFRESH_DEBOUNCE_MS = 200

---@class ow.lsp.codelens.Session
---@field buf integer
---@field enabled boolean
---@field attached boolean
---@field rows table<integer, ow.lsp.codelens.Row>
---@field current? ow.lsp.codelens.RefreshTask
local Session = {}
Session.__index = Session

---@type table<integer, ow.lsp.codelens.Session>
local by_buf = {}

---@param buf integer
local function do_refresh(buf)
    local session = by_buf[buf]
    if not session or not session.enabled then
        return
    end
    session:abort()
    local task = RefreshTask.new(session)
    session.current = task
    task:run()
end

local refresh, refresh_handle =
    util.keyed_debounce(do_refresh, REFRESH_DEBOUNCE_MS)

---@param buf integer
---@return ow.lsp.codelens.Session
function Session.get(buf)
    if not by_buf[buf] then
        by_buf[buf] = setmetatable({
            buf = buf,
            enabled = false,
            attached = false,
            rows = {},
        }, Session)
    end
    return by_buf[buf]
end

---@param buf integer
---@return ow.lsp.codelens.Session?
function Session.find(buf)
    return by_buf[buf]
end

---@return table<integer, ow.lsp.codelens.Session>
function Session.all()
    return by_buf
end

---@param buf integer
function Session.remove(buf)
    local session = by_buf[buf]
    if session then
        session:abort()
    end
    by_buf[buf] = nil
end

function Session:abort()
    refresh_handle.cancel(self.buf)
    if self.current then
        self.current:abort()
        self.current = nil
    end
end

function Session:refresh()
    refresh(self.buf)
end

function Session:render()
    if not vim.api.nvim_buf_is_valid(self.buf) then
        return
    end
    if not self.enabled then
        Row.clear_all(self.buf)
        return
    end

    for _, row in pairs(self.rows) do
        row:render(self.buf)
    end

    Row.prune(self.buf, self.rows)
end

function Session:attach()
    if self.attached then
        return
    end
    self.attached = true
    vim.api.nvim_buf_attach(self.buf, false, {
        on_lines = function()
            if not self.enabled then
                self.attached = false
                return true
            end
            self:refresh()
        end,
        on_reload = function()
            if self.enabled then
                self:refresh()
            end
        end,
        on_detach = function()
            self.attached = false
        end,
    })
end

---@param value boolean
function Session:enable(value)
    self.enabled = value
    if value then
        self:attach()
        self:refresh()
    else
        self:abort()
        self.rows = {}
        self:render()
    end
end

function Session:toggle()
    self:enable(not self.enabled)
end

return Session