local M = {}

-- Show/navigate warning and errors by default.
M.severity = vim.diagnostic.severity.WARN

-- Go to next/prev diagnostic, but only if next item has a visible virtual text.
-- If we can move, then also center screen at target location.
local conditional_jump = function(count)
  vim.validate("count", count, "number")

  local get_diagnostic = count > 0 and vim.diagnostic.get_next or vim.diagnostic.get_prev
  local diagnostic = get_diagnostic {
    wrap = false, -- don't wrap around the begin/end of file
    severity = { -- only navigate items with visible virtual text
      min = M.severity,
    },
  }

  if diagnostic then
    vim.diagnostic.jump { diagnostic = diagnostic, float = true }
    vim.cmd("normal zz")
  else
    local level = vim.diagnostic.severity[M.severity] or "???"
    local msg = string.format("No more diagnostics [level: %s]", level)
    vim.notify(msg, vim.log.levels.WARN)
  end
end

---Move to the next diagnostic.
M.goto_next = function() conditional_jump(1) end

---Move to the previous diagnostic.
M.goto_prev = function() conditional_jump(-1) end

---Show diagnostics in a floating window.
---@param opts table|nil: options passed along to `vim.diagnostic.open_float`.
M.open_float = function(opts) vim.diagnostic.open_float(opts) end

---Toggle diagnostics in the given buffer.
---@param bufnr integer|nil: Buffer number (0 for current buffer, nil for all buffers.
M.toggle = function(bufnr)
  local filter = { bufnr = bufnr or 0 }
  if vim.diagnostic.is_enabled(filter) then
    vim.diagnostic.enable(false, filter)
  else
    vim.diagnostic.enable(true, filter)
  end
end

---Hide currently displayed diagnostics.
---@param bufnr integer|nil: Buffer number (0 for current buffer, nil for all buffers.
M.hide = function(bufnr) vim.diagnostic.hide(nil, bufnr or 0) end

local icons = require("fschauen.util.icons")

---Select minimum diagnostic severity for which to show virtual text.
M.select_virtual_text_severity = function()
  if not pcall(require, "telescope") then
    vim.notify("Telescope not available!", vim.log.levels.ERROR)
    return
  end

  local display_row = require("telescope.pickers.entry_display").create {
    separator = "",
    items = { { width = 3 }, { remaining = true } },
  }

  local make_display = function(entry)
    return display_row {
      { entry.value.icon, entry.value.highlight },
      { entry.value.title, entry.value.highlight },
    }
  end

  local opts = require("telescope.themes").get_dropdown()
  require("telescope.pickers")
    .new(opts, {
      prompt_title = "Min. severity for virtual text:",
      finder = require("telescope.finders").new_table {
        results = {
          {
            title = "Error",
            severity = vim.diagnostic.severity.ERROR,
            icon = icons.diagnostics_bold.Error,
            highlight = "DiagnosticError",
          },
          {
            title = "Warning",
            severity = vim.diagnostic.severity.WARN,
            icon = icons.diagnostics_bold.Warn,
            highlight = "DiagnosticWarn",
          },
          {
            title = "Info",
            severity = vim.diagnostic.severity.INFO,
            icon = icons.diagnostics_bold.Info,
            highlight = "DiagnosticInfo",
          },
          {
            title = "Hint",
            severity = vim.diagnostic.severity.HINT,
            icon = icons.diagnostics_bold.Hint,
            highlight = "DiagnosticHint",
          },
        },
        entry_maker = function(entry)
          return { value = entry, ordinal = entry.title, display = make_display }
        end,
      },
      sorter = require("telescope.config").values.generic_sorter(opts),
      attach_mappings = function(prompt_bufnr, _)
        local actions = require("telescope.actions")
        actions.select_default:replace(function()
          actions.close(prompt_bufnr)
          local selection = require("telescope.actions.state").get_selected_entry()
          M.severity = selection.value.severity or M.severity
          vim.diagnostic.config {
            virtual_text = {
              severity = { min = M.severity },
            },
          }
        end)
        return true
      end,
    })
    :find()
end

---Customize nvim's diagnostics display.
M.setup = function()
  vim.diagnostic.config {
    underline = false,
    virtual_text = {
      spacing = 6,
      prefix = icons.ui.Circle,
      severity = {
        min = M.severity,
      },
    },
    float = {
      border = "rounded",
    },
    severity_sort = true,
  }

  for type, icon in pairs(icons.diagnostics) do
    local hl = "DiagnosticSign" .. type
    vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = hl })
  end
end

return M