-- Virtual buffer management module
local M = {}

local utils = require('notex.utils')

-- Active buffer management
local active_buffers = {}
local buffer_configs = {}

-- Create virtual buffer for query results
function M.create_query_buffer(query_results, options)
  options = options or {}

  local buffer_id = vim.api.nvim_create_buf(false, true) -- unlisted, scratch buffer

  if not buffer_id then
    return nil, "Failed to create virtual buffer"
  end

  -- Set buffer options
  M.setup_buffer_options(buffer_id, options)

  -- Generate buffer content
  local lines, syntax = M.generate_buffer_content(query_results, options)

  -- Set buffer content
  vim.api.nvim_buf_set_lines(buffer_id, 0, -1, false, lines)

  -- Set syntax highlighting
  if syntax then
    vim.api.nvim_buf_set_option(buffer_id, "filetype", syntax)
  end

  -- Create window if requested
  local window_id
  if options.create_window ~= false then
    window_id = M.create_query_window(buffer_id, options)
  end

  -- Store buffer configuration
  local config = {
    buffer_id = buffer_id,
    window_id = window_id,
    query_results = query_results,
    options = options,
    created_at = os.time(),
    mappings = M.setup_buffer_mappings(buffer_id, options)
  }

  active_buffers[buffer_id] = config
  buffer_configs[buffer_id] = config

  return config
end

-- Setup buffer options
function M.setup_buffer_options(buffer_id, options)
  local buf_opts = {
    buftype = "nofile",
    swapfile = false,
    bufhidden = "wipe",
    modifiable = options.modifiable or false,
    readonly = not (options.modifiable or false),
    textwidth = 0,
    wrapmargin = 0,
    wrap = options.wrap or false
  }

  for opt, value in pairs(buf_opts) do
    vim.api.nvim_buf_set_option(buffer_id, opt, value)
  end

  -- Set buffer name
  local buf_name = options.name or "notex://query-results"
  vim.api.nvim_buf_set_name(buffer_id, buf_name)
end

-- Generate buffer content from query results
function M.generate_buffer_content(query_results, options)
  local lines = {}
  local syntax = "notex"

  -- Add header
  table.insert(lines, "Query Results")
  table.insert(lines, string.rep("=", 50))
  table.insert(lines, "")

  -- Add query metadata
  if query_results.query_string then
    table.insert(lines, "Query: " .. query_results.query_string)
    table.insert(lines, "")
  end

  -- Add execution statistics
  table.insert(lines, string.format("Found %d documents (%.2fms)",
                                       query_results.total_count or 0,
                                       query_results.execution_time_ms or 0))
  table.insert(lines, "")

  -- Add document results
  if query_results.documents and #query_results.documents > 0 then
    lines = M.add_document_table(lines, query_results.documents, options)
  else
    table.insert(lines, "No documents found matching the query criteria.")
    table.insert(lines, "")
  end

  -- Add help section
  lines = M.add_help_section(lines, options)

  return lines, syntax
end

-- Add document table to buffer
function M.add_document_table(lines, documents, options)
  local max_width = options.max_width or 120
  local include_properties = options.include_properties or {"title", "status", "priority", "created_at"}

  -- Calculate column widths
  local column_widths = M.calculate_column_widths(documents, include_properties, max_width)

  -- Add table header
  local header_parts = {"#", "File"}
  for _, prop in ipairs(include_properties) do
    table.insert(header_parts, M.format_column_header(prop, column_widths[prop]))
  end
  table.insert(lines, table.concat(header_parts, " | "))

  -- Add separator
  local separator_parts = {"-", string.rep("-", 20)}
  for _, prop in ipairs(include_properties) do
    table.insert(separator_parts, string.rep("-", column_widths[prop]))
  end
  table.insert(lines, table.concat(separator_parts, " | "))
  table.insert(lines, "")

  -- Add document rows
  for i, doc in ipairs(documents) do
    local row_parts = {tostring(i), M.truncate_path(doc.file_path, 20)}

    for _, prop in ipairs(include_properties) do
      local value = doc.properties and doc.properties[prop] or ""
      local formatted_value = M.format_property_value(value, column_widths[prop])
      table.insert(row_parts, formatted_value)
    end

    table.insert(lines, table.concat(row_parts, " | "))
  end

  table.insert(lines, "")

  return lines
end

-- Calculate column widths for table
function M.calculate_column_widths(documents, properties, max_width)
  local widths = {}

  -- Set minimum widths based on property names
  for _, prop in ipairs(properties) do
    widths[prop] = math.max(#prop, 10)
  end

  -- Adjust based on content
  for _, doc in ipairs(documents) do
    for _, prop in ipairs(properties) do
      local value = doc.properties and doc.properties[prop] or ""
      local formatted = tostring(value)
      widths[prop] = math.max(widths[prop], #formatted)
    end
  end

  -- Limit maximum width
  local total_min_width = 30 -- # + File columns
  local available_width = max_width - total_min_width

  if #properties > 0 then
    local per_column = math.floor(available_width / #properties)
    for _, prop in ipairs(properties) do
      widths[prop] = math.min(widths[prop], per_column)
    end
  end

  return widths
end

-- Format column header
function M.format_column_header(property, width)
  local formatted = property:gsub("_", " "):gsub("(%a)([%w_]*)", function(first, rest)
    return first:upper() .. rest:lower()
  end)
  return M.pad_right(formatted, width)
end

-- Format property value for table
function M.format_property_value(value, width)
  if not value then
    return M.pad_right("", width)
  end

  local formatted = tostring(value)

  -- Truncate if too long
  if #formatted > width then
    formatted = formatted:sub(1, width - 3) .. "..."
  end

  return M.pad_right(formatted, width)
end

-- Truncate file path
function M.truncate_path(path, max_length)
  if #path <= max_length then
    return M.pad_right(path, max_length)
  end

  local filename = vim.fn.fnamemodify(path, ":t")
  local dirname = vim.fn.fnamemodify(path, ":h")

  if #filename + 3 <= max_length then
    local dir_length = max_length - #filename - 3
    local truncated_dir = dirname:sub(-dir_length)
    return M.pad_right("..." .. truncated_dir .. "/" .. filename, max_length)
  else
    return M.pad_right("..." .. filename:sub(-(max_length - 3)), max_length)
  end
end

-- Pad string to specified width
function M.pad_right(str, width)
  return str .. string.rep(" ", width - #str)
end

-- Add help section
function M.add_help_section(lines, options)
  if options.show_help == false then
    return lines
  end

  table.insert(lines, "Help:")
  table.insert(lines, "  <Enter>  - Open document under cursor")
  table.insert(lines, "  o       - Open document in new tab")
  table.insert(lines, "  e       - Edit document properties")
  table.insert(lines, "  s       - Save query")
  table.insert(lines, "  r       - Refresh results")
  table.insert(lines, "  q       - Close this view")
  table.insert(lines, "")
  table.insert(lines, "Press ? for more help")

  return lines
end

-- Create window for buffer
function M.create_query_window(buffer_id, options)
  local window_config = options.window or {}

  -- Default window configuration
  local default_config = {
    relative = "editor",
    width = math.min(120, vim.api.nvim_get_option_value("columns", {})),
    height = math.min(30, vim.api.nvim_get_option_value("lines", {}) - 5),
    row = 1,
    col = 1,
    border = "rounded",
    style = "minimal",
    title = " Query Results ",
    title_pos = "center"
  }

  -- Merge with user config
  local final_config = vim.tbl_deep_extend("force", default_config, window_config)

  local window_id = vim.api.nvim_open_win(buffer_id, true, final_config)

  if not window_id then
    return nil, "Failed to create window"
  end

  -- Set window options
  vim.api.nvim_win_set_option(window_id, "wrap", false)
  vim.api.nvim_win_set_option(window_id, "cursorline", true)
  vim.api.nvim_win_set_option(window_id, "number", false)
  vim.api.nvim_win_set_option(window_id, "relativenumber", false)
  vim.api.nvim_win_set_option(window_id, "signcolumn", "no")

  return window_id
end

-- Setup buffer mappings
function M.setup_buffer_mappings(buffer_id, options)
  local mappings = options.mappings or M.get_default_mappings()

  for key, action in pairs(mappings) do
    local mode = action.mode or "n"
    local opts = {
      buffer = buffer_id,
      noremap = true,
      silent = true,
      nowait = true
    }

    if type(action.callback) == "string" then
      vim.keymap.set(mode, key, action.callback, opts)
    elseif type(action.callback) == "function" then
      vim.keymap.set(mode, key, action.callback, opts)
    end
  end

  return mappings
end

-- Get default mappings
function M.get_default_mappings()
  return {
    ["<CR>"] = {
      callback = function()
        require('notex.ui.buffer').handle_enter_key()
      end,
      description = "Open document"
    },
    ["o"] = {
      callback = function()
        require('notex.ui.buffer').handle_open_tab()
      end,
      description = "Open in new tab"
    },
    ["e"] = {
      callback = function()
        require('notex.ui.buffer').handle_edit_mode()
      end,
      description = "Edit properties"
    },
    ["s"] = {
      callback = function()
        require('notex.ui.buffer').handle_save_query()
      end,
      description = "Save query"
    },
    ["r"] = {
      callback = function()
        require('notex.ui.buffer').handle_refresh()
      end,
      description = "Refresh results"
    },
    ["q"] = {
      callback = function()
        require('notex.ui.buffer').handle_close_buffer()
      end,
      description = "Close buffer"
    },
    ["?"] = {
      callback = function()
        require('notex.ui.buffer').show_help()
      end,
      description = "Show help"
    },
    ["<Esc>"] = {
      callback = function()
        require('notex.ui.buffer').handle_close_buffer()
      end,
      description = "Close buffer"
    }
  }
end

-- Handle Enter key - open document
function M.handle_enter_key()
  local line = vim.api.nvim_get_current_line()
  local cursor = vim.api.nvim_win_get_cursor(0)
  local line_num = cursor[1]

  -- Skip header lines
  if line_num < 6 then
    return
  end

  -- Extract file path from line
  local file_path = M.extract_file_path_from_line(line)
  if file_path and utils.file_exists(file_path) then
    vim.cmd('edit ' .. file_path)
  else
    vim.notify("Cannot open file: " .. (file_path or "unknown"), vim.log.levels.WARN)
  end
end

-- Handle open in new tab
function M.handle_open_tab()
  local line = vim.api.nvim_get_current_line()
  local file_path = M.extract_file_path_from_line(line)

  if file_path and utils.file_exists(file_path) then
    vim.cmd('tabedit ' .. file_path)
  else
    vim.notify("Cannot open file: " .. (file_path or "unknown"), vim.log.levels.WARN)
  end
end

-- Handle edit mode
function M.handle_edit_mode()
  local buffer = vim.api.nvim_get_current_buf()
  vim.api.nvim_buf_set_option(buffer, "modifiable", true)
  vim.notify("Edit mode enabled - press <Esc> to save and exit", vim.log.levels.INFO)
end

-- Handle save query
function M.handle_save_query()
  local config = buffer_configs[vim.api.nvim_get_current_buf()]
  if not config or not config.query_results then
    return
  end

  vim.ui.input({ prompt = "Query name: " }, function(query_name)
    if query_name and query_name ~= "" then
      local query_engine = require('notex.query')
      local result = query_engine.save_query(query_name, config.query_results.query_string)

      if result.success then
        vim.notify("Query saved: " .. query_name, vim.log.levels.INFO)
      else
        vim.notify("Failed to save query: " .. result.error, vim.log.levels.ERROR)
      end
    end
  end)
end

-- Handle refresh
function M.handle_refresh()
  local config = buffer_configs[vim.api.nvim_get_current_buf()]
  if not config or not config.query_results or not config.query_results.query_string then
    return
  end

  -- Re-execute query
  local query_engine = require('notex.query')
  local result = query_engine.execute_query(config.query_results.query_string)

  if result.success then
    -- Update buffer content
    local lines, _ = M.generate_buffer_content(result, config.options)
    vim.api.nvim_buf_set_lines(vim.api.nvim_get_current_buf(), 0, -1, false, lines)

    -- Update config
    config.query_results = result

    vim.notify("Query refreshed", vim.log.levels.INFO)
  else
    vim.notify("Failed to refresh query: " .. table.concat(result.errors, ", "), vim.log.levels.ERROR)
  end
end

-- Handle close buffer
function M.handle_close_buffer()
  local buffer = vim.api.nvim_get_current_buf()
  local config = active_buffers[buffer]

  if config and config.window_id then
    vim.api.nvim_win_close(config.window_id, true)
  else
    vim.cmd('bdelete!')
  end
end

-- Show help
function M.show_help()
  local help_content = [[
Notex Query Results Help:

Navigation:
  <Enter>    - Open document under cursor
  o          - Open document in new tab
  q          - Close this view
  <Esc>      - Close this view

Actions:
  e          - Enable edit mode for modifying results
  s          - Save current query for reuse
  r          - Refresh query results

Other:
  ?          - Show this help
  j/k        - Move up/down
  gg/G       - Go to top/bottom
  /pattern   - Search in results

Press any key to close this help
]]

  local buf = vim.api.nvim_create_buf(false, true)
  vim.api.nvim_buf_set_lines(buf, 0, -1, false, vim.split(help_content, "\n"))
  vim.api.nvim_buf_set_option(buf, "filetype", "help")

  local win_id = vim.api.nvim_open_win(buf, true, {
    relative = "editor",
    width = 60,
    height = 20,
    row = math.floor((vim.api.nvim_get_option_value("lines", {}) - 20) / 2),
    col = math.floor((vim.api.nvim_get_option_value("columns", {}) - 60) / 2),
    border = "rounded",
    style = "minimal",
    title = " Help "
  })

  vim.api.nvim_win_set_option(win_id, "wrap", true)

  -- Close help on any key
  vim.api.nvim_create_autocmd("CursorMoved,WinLeave", {
    buffer = buf,
    once = true,
    callback = function()
      vim.api.nvim_win_close(win_id, true)
    end
  })
end

-- Extract file path from line
function M.extract_file_path_from_line(line)
  -- Match file path in table row
  local match = line:match("^%s*%d+%s+|?%s*([^|]+)")
  if match then
    -- Clean up the path
    local path = match:trim()
    path = path:gsub("%s+$", "") -- Remove trailing spaces
    return path
  end

  return nil
end

-- Get active buffer configurations
function M.get_active_buffers()
  local configs = {}
  for buffer_id, config in pairs(active_buffers) do
    if vim.api.nvim_buf_is_valid(buffer_id) then
      configs[buffer_id] = config
    else
      -- Clean up invalid buffers
      active_buffers[buffer_id] = nil
      buffer_configs[buffer_id] = nil
    end
  end

  return configs
end

-- Clean up inactive buffers
function M.cleanup_buffers()
  local to_remove = {}

  for buffer_id, config in pairs(active_buffers) do
    if not vim.api.nvim_buf_is_valid(buffer_id) then
      table.insert(to_remove, buffer_id)
    end
  end

  for _, buffer_id in ipairs(to_remove) do
    active_buffers[buffer_id] = nil
    buffer_configs[buffer_id] = nil
  end
end

return M