nvim-config/lua/mail.lua

-- Mail compose mode: NeoMutt + nvim-mail integration.
-- Activates ONLY when the NEOMUTT environment variable is set.
-- In neomuttrc: set editor = "env NEOMUTT=1 nvim"
--
-- Notmuch: optional indexed search only via <leader>mn. Never initialised or synced.
-- mbsync: never invoked.

local M = {}

-- Exact-match guard: only "1" activates mail mode.
-- Any other value (empty, "yes", "true") leaves this module dormant.
local function in_neomutt()
  return vim.env.NEOMUTT == "1"
end

if not in_neomutt() then
  return M
end

-- === NeoMutt session active ===

local function is_tty()
  return vim.env.TERM == "linux"
end

-- Configure nvim-mail (idempotent: the plugin guards with _configured flag).
local ok_mail, mail_plugin = pcall(require, "nvim-mail")
if ok_mail then
  mail_plugin.setup({
    prefix = ",m",
    spell_langs = { "en" },
    from_list = {},
    send_accounts = {},
    contacts = { cmd = "khard", args = { "email", "-p", "--remove-first-line" } },
    snippets = nil,
  })
end

-- FileType autocmd: 72-column compose formatting + quote-depth highlighting.
-- nvim-mail's attach_buffer() handles spell, wrap, marker extmarks, and
-- BufWritePre guardrails (empty To/Subject, attachment mention check).
local au = vim.api.nvim_create_augroup("NeoMuttMail", { clear = true })
vim.api.nvim_create_autocmd("FileType", {
  group = au,
  pattern = "mail",
  callback = function()
    vim.opt_local.textwidth = 72
    vim.opt_local.formatoptions = "tcqwan"
    vim.opt_local.wrap = true
    vim.opt_local.linebreak = true
    vim.opt_local.spell = true
    vim.opt_local.spelllang = "en"
    -- colorcolumn is meaningful only outside TTY (linux console ignores it)
    if not is_tty() then
      vim.opt_local.colorcolumn = "73"
    end
    -- Quote-depth colouring: works with both cterm (TTY) and gui colours
    vim.cmd([[
      hi def MailQuoted1 ctermfg=6  guifg=#61afef
      hi def MailQuoted2 ctermfg=2  guifg=#98c379
      hi def MailQuoted3 ctermfg=3  guifg=#e5c07b
      syn match MailQuoted3 /^>>>\+.*$/
      syn match MailQuoted2 /^>>[^>].*$\|^>>$/
      syn match MailQuoted1 /^>[^>].*$\|^>$/
    ]])
  end,
})

-- <leader>m group: mail compose actions (supplement to nvim-mail's ,m prefix).
-- Descriptions are plain ASCII so they render correctly in TTY via which-key.
local km = function(lhs, rhs, desc)
  vim.keymap.set("n", lhs, rhs, { desc = desc })
end

km("<leader>m", "", "Mail")

-- NeoMutt's Neovim Lua runtime may be LuaJIT/Lua 5.1, which exposes only global unpack.
local unpack_args = table.unpack or unpack

-- Safe wrapper: pcall so the keymap degrades gracefully if plugin not yet downloaded.
local function nav(fn, ...)
  local args = { ... }
  local ok, nav_mod = pcall(require, "nvim-mail.navigate")
  if ok then nav_mod[fn](unpack_args(args)) end
end

km("<leader>mt", function() nav("goto_field", "^[Tt]o:", "A") end, "Mail: To:")
km("<leader>mc", function() nav("goto_field", "^[Cc]c:", "A") end, "Mail: Cc:")
km("<leader>mf", function() nav("goto_field", "^[Ff]rom:", "A") end, "Mail: From:")
km("<leader>ms", function() nav("goto_field", "^[Ss]ubject:", "A") end, "Mail: Subject:")
km("<leader>mb", function() nav("goto_body") end, "Mail: Body")
km("<leader>mS", function() nav("goto_signature") end, "Mail: Signature")
km("<leader>mr", function() nav("goto_reply") end, "Mail: Quoted reply")
km("<leader>me", function() nav("goto_end_of_reply") end, "Mail: End of reply")
km("<leader>mk", function() nav("kill_quoted_sig") end, "Mail: Kill quoted sig")

-- Attachment guardrail: on-demand explicit check (BufWritePre also fires automatically)
km("<leader>ma", function()
  local lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
  local ok_att, att = pcall(require, "nvim-mail.attachment")
  if not ok_att then
    vim.notify("[mail] nvim-mail.attachment unavailable", vim.log.levels.ERROR)
    return
  end
  local missing, match = att.check(lines)
  if missing then
    vim.notify(
      string.format('[mail] Attachment mentioned ("%s") but no file attached!', match or "attach"),
      vim.log.levels.WARN
    )
  else
    vim.notify("[mail] Attachment check: OK", vim.log.levels.INFO)
  end
end, "Mail: Attachment check")

-- Header reminder: warn if To: or Subject: are empty
km("<leader>mR", function()
  local lines = vim.api.nvim_buf_get_lines(0, 0, 20, false)
  local to, subj = false, false
  for _, l in ipairs(lines) do
    if l == "" then break end
    if l:match("^[Tt]o:%s*.+") then to = true end
    if l:match("^[Ss]ubject:%s*.+") then subj = true end
  end
  local issues = {}
  if not to then issues[#issues + 1] = "To: is empty" end
  if not subj then issues[#issues + 1] = "Subject: is empty" end
  if #issues == 0 then
    vim.notify("[mail] Headers OK", vim.log.levels.INFO)
  else
    vim.notify("[mail] " .. table.concat(issues, " | "), vim.log.levels.WARN)
  end
end, "Mail: Header reminder")

-- Notmuch: optional indexed search only. Never initialised, never synced.
-- Opens results in a scratch buffer; does not touch the notmuch database.
km("<leader>mn", function()
  if vim.fn.executable("notmuch") == 0 then
    vim.notify("[mail] notmuch not available (optional dependency)", vim.log.levels.WARN)
    return
  end
  vim.ui.input({ prompt = "Notmuch search: " }, function(query)
    if not query or query == "" then return end
    local result = vim.fn.systemlist({ "notmuch", "search", "--output=summary", query })
    vim.cmd("new")
    vim.api.nvim_buf_set_lines(0, 0, -1, false, result)
    vim.bo.buftype = "nofile"
    vim.bo.bufhidden = "wipe"
    vim.bo.modifiable = false
    vim.bo.swapfile = false
    pcall(vim.api.nvim_buf_set_name, 0, "Notmuch: " .. query)
  end)
end, "Mail: Notmuch search")

return M