feat: add health checks

Author: Marc Jakobi

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Health checks.
 - Use tree-sitter if the parser for Haskell is installed,
   without requiring the nvim-treesitter plugin.
 

lua/haskell-snippets/health.lua

@@ -0,0 +1,105 @@
+local health = {}
+
+local h = vim.health or require('health')
+local start = h.start or h.report_start
+local ok = h.ok or h.report_ok
+local error = h.error or h.report_error
+local warn = h.warn or h.report_warn
+
+---@class ExternalDependency
+---@field name string Name of the dependency
+---@field get_binaries fun():string[]Function that returns the binaries to check for
+---@field optional fun():boolean Function that returns whether the dependency is optional
+---@field url string URL (markdown)
+---@field info string Additional information
+---@field extra_checks function|nil Optional extra checks to perform if the dependency is installed
+
+---@type ExternalDependency[]
+local external_dependencies = {
+  {
+    name = 'haskell-language-server',
+    get_binaries = function()
+      local _, HTConfig = pcall(require, 'haskell-tools.config.internal')
+      local default = { 'haskell-language-server-wrapper', 'haskell-language-server' }
+      if not HTConfig then
+        return default
+      end
+      local Types = require('haskell-tools.types.internal')
+      local cmd = Types.evaluate(HTConfig.hls.cmd)
+      if not cmd or #cmd == 0 then
+        return default
+      end
+      return { cmd[1] }
+    end,
+    optional = function()
+      return true
+    end,
+    url = '[haskell-language-server](https://haskell-language-server.readthedocs.io)',
+    info = 'Some snippets work better with LSP.',
+  },
+}
+
+---@param dep ExternalDependency
+---@return boolean is_installed
+---@return string|nil version
+local check_installed = function(dep)
+  local binaries = dep.get_binaries()
+  for _, binary in ipairs(binaries) do
+    if vim.fn.executable(binary) == 1 then
+      local handle = io.popen(binary .. ' --version')
+      if handle then
+        local binary_version, error_msg = handle:read('*a')
+        handle:close()
+        if error_msg then
+          return true
+        end
+        return true, binary_version
+      end
+      return true
+    end
+  end
+  return false
+end
+
+---@param dep ExternalDependency
+local function check_external_dependency(dep)
+  local installed, mb_version = check_installed(dep)
+  if installed then
+    local version = mb_version and mb_version:sub(0, mb_version:find('\n') - 1) or '(unknown version)'
+    ok(('%s: found %s.'):format(dep.name, version))
+    if dep.extra_checks then
+      dep.extra_checks()
+    end
+    return
+  end
+  if dep.optional() then
+    warn(([[
+      %s: not found.
+      Install %s for extended capabilities.
+      %s
+      ]]):format(dep.name, dep.url, dep.info))
+  else
+    error(([[
+      %s: not found.
+      haskell-snippets.nvim requires %s.
+      %s
+      ]]):format(dep.name, dep.url, dep.info))
+  end
+end
+
+function health.check()
+  start('Checking external dependencies')
+  for _, dep in ipairs(external_dependencies) do
+    check_external_dependency(dep)
+  end
+
+  start('Checking tree-sitter parsers')
+  local success = pcall(vim.treesitter.get_string_parser, '', 'haskell')
+  if not success then
+    warn('The tree-sitter parser for Haskell is not installed.')
+  else
+    ok('The tree-sitter parser for Haskell is installed.')
+  end
+end
+
+return health