local M = {}

-- All highlight groups: linked or directly defined.
-- Please add new groups to help and preserve order.
-- Please avoid directly defined groups to preserve accessibility for TUI.
M.HIGHLIGHT_GROUPS = {

  -- Standard
  { group = "NvimTreeNormal", link = "Normal" },
  { group = "NvimTreeNormalFloat", link = "NormalFloat" },
  { group = "NvimTreeNormalNC", link = "NvimTreeNormal" },

  { group = "NvimTreeLineNr", link = "LineNr" },
  { group = "NvimTreeWinSeparator", link = "WinSeparator" },
  { group = "NvimTreeEndOfBuffer", link = "EndOfBuffer" },
  { group = "NvimTreePopup", link = "Normal" },
  { group = "NvimTreeSignColumn", link = "NvimTreeNormal" },

  { group = "NvimTreeCursorColumn", link = "CursorColumn" },
  { group = "NvimTreeCursorLine", link = "CursorLine" },
  { group = "NvimTreeCursorLineNr", link = "CursorLineNr" },

  { group = "NvimTreeStatusLine", link = "StatusLine" },
  { group = "NvimTreeStatusLineNC", link = "StatusLineNC" },

  -- File Text
  { group = "NvimTreeExecFile", link = "SpellCap" },
  { group = "NvimTreeImageFile", link = "SpellCap" },
  { group = "NvimTreeSpecialFile", link = "SpellCap" },
  { group = "NvimTreeSymlink", link = "SpellCap" },

  -- Folder Text
  { group = "NvimTreeRootFolder", link = "Title" },
  { group = "NvimTreeFolderName", link = "Directory" },
  { group = "NvimTreeEmptyFolderName", link = "Directory" },
  { group = "NvimTreeOpenedFolderName", link = "Directory" },
  { group = "NvimTreeSymlinkFolderName", link = "Directory" },

  -- File Icons
  { group = "NvimTreeFileIcon", link = "NvimTreeNormal" },
  { group = "NvimTreeSymlinkIcon", link = "NvimTreeNormal" },

  -- Folder Icons
  { group = "NvimTreeFolderIcon", def = "guifg=#8094b4 ctermfg=Blue" },
  { group = "NvimTreeOpenedFolderIcon", link = "NvimTreeFolderIcon" },
  { group = "NvimTreeClosedFolderIcon", link = "NvimTreeFolderIcon" },
  { group = "NvimTreeFolderArrowClosed", link = "NvimTreeIndentMarker" },
  { group = "NvimTreeFolderArrowOpen", link = "NvimTreeIndentMarker" },

  -- Indent
  { group = "NvimTreeIndentMarker", link = "NvimTreeFolderIcon" },

  -- Picker
  { group = "NvimTreeWindowPicker", def = "guifg=#ededed guibg=#4493c8 gui=bold ctermfg=White ctermbg=Cyan" },

  -- LiveFilter
  { group = "NvimTreeLiveFilterPrefix", link = "PreProc" },
  { group = "NvimTreeLiveFilterValue", link = "ModeMsg" },

  -- Clipboard
  { group = "NvimTreeCutHL", link = "SpellBad" },
  { group = "NvimTreeCopiedHL", link = "SpellRare" },

  -- Bookmark
  { group = "NvimTreeBookmarkIcon", link = "NvimTreeFolderIcon" },
  { group = "NvimTreeBookmarkHL", link = "SpellLocal" },

  -- Modified
  { group = "NvimTreeModifiedIcon", link = "Type" },
  { group = "NvimTreeModifiedFileHL", link = "NvimTreeModifiedIcon" },
  { group = "NvimTreeModifiedFolderHL", link = "NvimTreeModifiedFileHL" },

  -- Opened
  { group = "NvimTreeOpenedHL", link = "Special" },

  -- Git Icon
  { group = "NvimTreeGitDeletedIcon", link = "Statement" },
  { group = "NvimTreeGitDirtyIcon", link = "Statement" },
  { group = "NvimTreeGitIgnoredIcon", link = "Comment" },
  { group = "NvimTreeGitMergeIcon", link = "Constant" },
  { group = "NvimTreeGitNewIcon", link = "PreProc" },
  { group = "NvimTreeGitRenamedIcon", link = "PreProc" },
  { group = "NvimTreeGitStagedIcon", link = "Constant" },

  -- Git File Highlight
  { group = "NvimTreeGitFileDeletedHL", link = "NvimTreeGitDeletedIcon" },
  { group = "NvimTreeGitFileDirtyHL", link = "NvimTreeGitDirtyIcon" },
  { group = "NvimTreeGitFileIgnoredHL", link = "NvimTreeGitIgnoredIcon" },
  { group = "NvimTreeGitFileMergeHL", link = "NvimTreeGitMergeIcon" },
  { group = "NvimTreeGitFileNewHL", link = "NvimTreeGitNewIcon" },
  { group = "NvimTreeGitFileRenamedHL", link = "NvimTreeGitRenamedIcon" },
  { group = "NvimTreeGitFileStagedHL", link = "NvimTreeGitStagedIcon" },

  -- Git Folder Highlight
  { group = "NvimTreeGitFolderDeletedHL", link = "NvimTreeGitFileDeletedHL" },
  { group = "NvimTreeGitFolderDirtyHL", link = "NvimTreeGitFileDirtyHL" },
  { group = "NvimTreeGitFolderIgnoredHL", link = "NvimTreeGitFileIgnoredHL" },
  { group = "NvimTreeGitFolderMergeHL", link = "NvimTreeGitFileMergeHL" },
  { group = "NvimTreeGitFolderNewHL", link = "NvimTreeGitFileNewHL" },
  { group = "NvimTreeGitFolderRenamedHL", link = "NvimTreeGitFileRenamedHL" },
  { group = "NvimTreeGitFolderStagedHL", link = "NvimTreeGitFileStagedHL" },

  -- Diagnostics Icon
  { group = "NvimTreeDiagnosticErrorIcon", link = "DiagnosticError" },
  { group = "NvimTreeDiagnosticWarnIcon", link = "DiagnosticWarn" },
  { group = "NvimTreeDiagnosticInfoIcon", link = "DiagnosticInfo" },
  { group = "NvimTreeDiagnosticHintIcon", link = "DiagnosticHint" },

  -- Diagnostics File Highlight
  { group = "NvimTreeDiagnosticErrorFileHL", link = "DiagnosticUnderlineError" },
  { group = "NvimTreeDiagnosticWarnFileHL", link = "DiagnosticUnderlineWarn" },
  { group = "NvimTreeDiagnosticInfoFileHL", link = "DiagnosticUnderlineInfo" },
  { group = "NvimTreeDiagnosticHintFileHL", link = "DiagnosticUnderlineHint" },

  -- Diagnostics Folder Highlight
  { group = "NvimTreeDiagnosticErrorFolderHL", link = "NvimTreeDiagnosticErrorFileHL" },
  { group = "NvimTreeDiagnosticWarnFolderHL", link = "NvimTreeDiagnosticWarnFileHL" },
  { group = "NvimTreeDiagnosticInfoFolderHL", link = "NvimTreeDiagnosticInfoFileHL" },
  { group = "NvimTreeDiagnosticHintFolderHL", link = "NvimTreeDiagnosticHintFileHL" },
}

-- nvim-tree highlight groups to legacy
M.LEGACY_LINKS = {
  NvimTreeModifiedIcon = "NvimTreeModifiedFile",

  NvimTreeOpenedHL = "NvimTreeOpenedFile",

  NvimTreeBookmarkIcon = "NvimTreeBookmark",

  NvimTreeGitDeletedIcon = "NvimTreeGitDeleted",
  NvimTreeGitDirtyIcon = "NvimTreeGitDirty",
  NvimTreeGitIgnoredIcon = "NvimTreeGitIgnored",
  NvimTreeGitMergeIcon = "NvimTreeGitMerge",
  NvimTreeGitNewIcon = "NvimTreeGitNew",
  NvimTreeGitRenamedIcon = "NvimTreeGitRenamed",
  NvimTreeGitStagedIcon = "NvimTreeGitStaged",

  NvimTreeGitFileDeletedHL = "NvimTreeFileDeleted",
  NvimTreeGitFileDirtyHL = "NvimTreeFileDirty",
  NvimTreeGitFileIgnoredHL = "NvimTreeFileIgnored",
  NvimTreeGitFileMergeHL = "NvimTreeFileMerge",
  NvimTreeGitFileNewHL = "NvimTreeFileNew",
  NvimTreeGitFileRenamedHL = "NvimTreeFileRenamed",
  NvimTreeGitFileStagedHL = "NvimTreeFileStaged",

  NvimTreeGitFolderDeletedHL = "NvimTreeFolderDeleted",
  NvimTreeGitFolderDirtyHL = "NvimTreeFolderDirty",
  NvimTreeGitFolderIgnoredHL = "NvimTreeFolderIgnored",
  NvimTreeGitFolderMergeHL = "NvimTreeFolderMerge",
  NvimTreeGitFolderNewHL = "NvimTreeFolderNew",
  NvimTreeGitFolderRenamedHL = "NvimTreeFolderRenamed",
  NvimTreeGitFolderStagedHL = "NvimTreeFolderStaged",

  NvimTreeDiagnosticErrorIcon = "NvimTreeLspDiagnosticsError",
  NvimTreeDiagnosticWarnIcon = "NvimTreeLspDiagnosticsWarning",
  NvimTreeDiagnosticInfoIcon = "NvimTreeLspDiagnosticsInformation",
  NvimTreeDiagnosticHintIcon = "NvimTreeLspDiagnosticsHint",

  NvimTreeDiagnosticErrorFileHL = "NvimTreeLspDiagnosticsErrorText",
  NvimTreeDiagnosticWarnFileHL = "NvimTreeLspDiagnosticsWarningText",
  NvimTreeDiagnosticInfoFileHL = "NvimTreeLspDiagnosticsInformationText",
  NvimTreeDiagnosticHintFileHL = "NvimTreeLspDiagnosticsHintText",

  NvimTreeDiagnosticErrorFolderHL = "NvimTreeLspDiagnosticsErrorFolderText",
  NvimTreeDiagnosticWarnFolderHL = "NvimTreeLspDiagnosticsWarningFolderText",
  NvimTreeDiagnosticInfoFolderHL = "NvimTreeLspDiagnosticsInformationFolderText",
  NvimTreeDiagnosticHintFolderHL = "NvimTreeLspDiagnosticsHintFolderText",
}

function M.setup()
  -- non-linked
  for _, g in ipairs(M.HIGHLIGHT_GROUPS) do
    if g.def then
      vim.api.nvim_command("hi def " .. g.group .. " " .. g.def)
    end
  end

  -- hard link override when legacy only is present
  for from, to in pairs(M.LEGACY_LINKS) do
    local hl_from
    local hl_to
    if vim.fn.has "nvim-0.9" == 1 then
      hl_from = vim.api.nvim_get_hl(0, { name = from })
      hl_to = vim.api.nvim_get_hl(0, { name = to })
    else
      hl_from = vim.api.nvim__get_hl_defs(0)[from] or {}
      hl_to = vim.api.nvim__get_hl_defs(0)[to] or {}
    end
    if vim.tbl_isempty(hl_from) and not vim.tbl_isempty(hl_to) then
      vim.api.nvim_command("hi link " .. from .. " " .. to)
    end
  end

  -- default links
  for _, g in ipairs(M.HIGHLIGHT_GROUPS) do
    if g.link then
      vim.api.nvim_command("hi def link " .. g.group .. " " .. g.link)
    end
  end
end

return M