-- This module is responsible for creating am MR
-- for the current branch
local Layout = require("nui.layout")
local Input = require("nui.input")
local Popup = require("nui.popup")
local job = require("gitlab.job")
local u = require("gitlab.utils")
local state = require("gitlab.state")
local miscellaneous = require("gitlab.actions.miscellaneous")

---@class Mr
---@field target? string
---@field title? string
---@field description? string

---@class Args
---@field target? string
---@field template_file? string

local M = {
  started = false,
  layout_visible = false,
  layout = nil,
  layout_buf = nil,
  title_bufnr = nil,
  description_bufnr = nil,
  mr = {
    target = "",
    title = "",
    description = "",
  },
}

M.reset_state = function()
  M.started = false
  M.mr.title = ""
  M.mr.target = ""
  M.mr.description = ""
end

local title_popup_settings = {
  buf_options = {
    filetype = "markdown",
  },
  focusable = true,
  border = {
    style = "rounded",
    text = {
      top = "Title",
    },
  },
}

local target_popup_settings = {
  buf_options = {
    filetype = "markdown",
  },
  focusable = true,
  border = {
    style = "rounded",
    text = {
      top = "Target branch",
    },
  },
}

local description_popup_settings = {
  buf_options = {
    filetype = "markdown",
  },
  enter = true,
  focusable = true,
  border = {
    style = "rounded",
    text = {
      top = "Description",
    },
  },
}

local title_input_options = {
  position = "50%",
  relative = "editor",
  size = 40,
  border = {
    style = "rounded",
    text = {
      top = "Title",
    },
  },
}

---1. If the user has already begun writing an MR, prompt them to
--- continue working on it.
---@param args? Args
M.start = function(args)
  if M.started then
    vim.ui.select({ "Yes", "No" }, { prompt = "Continue your previous MR?" }, function(choice)
      if choice == "Yes" then
        M.open_confirmation_popup(M.mr)
        return
      else
        M.reset_state()
        M.pick_target(args)
      end
    end)
  else
    M.pick_target(args)
  end
end

---2. Pick the target branch
---@param args? Args
M.pick_target = function(args)
  if not args then
    args = {}
  end
  if args.target ~= nil then
    M.pick_template({ target = args.target }, args)
    return
  end

  if state.settings.create_mr.target ~= nil then
    M.pick_template({ target = state.settings.create_mr.target }, args)
    return
  end

  local all_branch_names = u.get_all_git_branches(true)
  vim.ui.select(all_branch_names, {
    prompt = "Choose target branch for merge",
  }, function(choice)
    if choice then
      M.pick_template({ target = choice }, args)
    end
  end)
end

local function make_template_path(t)
  local base_dir = vim.fn.trim(vim.fn.system({ "git", "rev-parse", "--show-toplevel" }))
  return base_dir
    .. state.settings.file_separator
    .. ".gitlab"
    .. state.settings.file_separator
    .. "merge_request_templates"
    .. state.settings.file_separator
    .. t
end

---3. Pick template (if applicable). This is used as the description
---@param mr Mr
---@param args Args
M.pick_template = function(mr, args)
  if not args then
    args = {}
  end

  local template_file = args.template_file or state.settings.create_mr.template_file
  if template_file ~= nil then
    local description = u.read_file(make_template_path(template_file))
    M.add_title({ target = mr.target, description = description })
    return
  end

  local all_templates = u.list_files_in_folder(".gitlab" .. state.settings.file_separator .. "merge_request_templates")
  if all_templates == nil then
    M.add_title({ target = mr.target })
    return
  end

  local opts = { "Blank Template" }
  for _, v in ipairs(all_templates) do
    table.insert(opts, v)
  end
  vim.ui.select(opts, {
    prompt = "Choose Template",
  }, function(choice)
    if choice then
      local description = u.read_file(make_template_path(choice))
      M.add_title({ target = mr.target, description = description })
    elseif choice == "Blank Template" then
      M.add_title({ target = mr.target })
    end
  end)
end

---4. Prompts the user for the title of the MR
---@param mr Mr
M.add_title = function(mr)
  local input = Input(title_input_options, {
    prompt = "",
    default_value = "",
    on_close = function() end,
    on_submit = function(_value)
      M.open_confirmation_popup(mr)
    end,
    on_change = function(value)
      mr.title = value
    end,
  })
  input:map("n", "<Esc>", function()
    input:unmount()
  end, { noremap = true })

  input:mount()
end

---5. Show the final popup.
---The function will render a popup containing the MR title and MR description, and
---target branch. The title and description are editable.
---@param mr Mr
M.open_confirmation_popup = function(mr)
  M.started = true
  if M.layout_visible then
    M.layout:unmount()
    M.layout_visible = false
    return
  end

  local layout, title_popup, description_popup, target_popup = M.create_layout()

  M.layout = layout
  M.layout_buf = layout.bufnr
  M.layout_visible = true

  local function exit()
    local title = vim.fn.trim(u.get_buffer_text(M.title_bufnr))
    local description = u.get_buffer_text(M.description_bufnr)
    local target = vim.fn.trim(u.get_buffer_text(target_popup.bufnr))
    M.mr = {
      title = title,
      description = description,
      target = target,
    }
    layout:unmount()
    M.layout_visible = false
  end

  local description_lines = mr.description and M.build_description_lines(mr.description) or { "" }

  vim.schedule(function()
    vim.api.nvim_buf_set_lines(description_popup.bufnr, 0, -1, false, description_lines)
    vim.api.nvim_buf_set_lines(title_popup.bufnr, 0, -1, false, { mr.title })
    vim.api.nvim_buf_set_lines(target_popup.bufnr, 0, -1, false, { mr.target })

    local popup_opts = {
      cb = exit,
      action_before_close = true,
      action_before_exit = true,
    }

    state.set_popup_keymaps(description_popup, M.create_mr, miscellaneous.attach_file, popup_opts)
    state.set_popup_keymaps(title_popup, M.create_mr, nil, popup_opts)
    state.set_popup_keymaps(target_popup, M.create_mr, nil, popup_opts)

    vim.api.nvim_set_current_buf(description_popup.bufnr)
  end)
end

---Builds a lua list of strings that contain the MR description
M.build_description_lines = function(template_content)
  local description_lines = {}
  for line in u.split_by_new_lines(template_content) do
    table.insert(description_lines, line)
  end
  -- TODO: @harrisoncramer Same as in lua/gitlab/actions/summary.lua:114
  table.insert(description_lines, "")

  return description_lines
end

---This function will POST the new MR to create it
M.create_mr = function()
  local description = u.get_buffer_text(M.description_bufnr)
  local title = u.get_buffer_text(M.title_bufnr):gsub("\n", " ")
  local target = u.get_buffer_text(M.target_bufnr):gsub("\n", " ")

  local body = {
    title = title,
    description = description,
    target_branch = target,
  }

  job.run_job("/create_mr", "POST", body, function(data)
    u.notify(data.message, vim.log.levels.INFO)
    M.reset_state()
    M.layout:unmount()
    M.layout_visible = false
  end)
end

M.create_layout = function()
  local title_popup = Popup(title_popup_settings)
  M.title_bufnr = title_popup.bufnr
  local description_popup = Popup(description_popup_settings)
  M.description_bufnr = description_popup.bufnr
  local target_branch_popup = Popup(target_popup_settings)
  M.target_bufnr = target_branch_popup.bufnr

  local internal_layout
  internal_layout = Layout.Box({
    Layout.Box({
      Layout.Box(title_popup, { grow = 1 }),
      Layout.Box(target_branch_popup, { grow = 1 }),
    }, { size = 3 }),
    Layout.Box(description_popup, { grow = 1 }),
  }, { dir = "col" })

  local layout = Layout({
    position = "50%",
    relative = "editor",
    size = {
      width = "95%",
      height = "95%",
    },
  }, internal_layout)

  layout:mount()

  return layout, title_popup, description_popup, target_branch_popup
end

return M