local utils = require"jsonfly.utils"


local M = {};

-- https://stackoverflow.com/a/24823383/9878135
function table.slice(tbl, first, last, step)
  local sliced = {}

  for i = first or 1, last or #tbl, step or 1 do
    sliced[#sliced+1] = tbl[i]
  end

  return sliced
end

---@param entry Entry
---@param key string
---@param index number
local function check_key_equal(entry, key, index)
    local splitted = utils:split_by_char(entry.key, ".")

    return splitted[index] == key
end

---Find the entry in `entries` with the most matching keys at the beginning based on the `keys`.
---Returns the index of the entry
---@param entries Entry[]
---@param keys KeyDescription[]
---@return number|nil
local function find_best_fitting_entry(entries, keys)
    local entry_index
    local current_indexes = {1, #entries}

    for kk=1, #keys do
        local key = keys[kk].key

        local start_index = current_indexes[1]
        local end_index = current_indexes[2]

        current_indexes = {nil, nil}

        for ii=start_index, end_index do
            if check_key_equal(entries[ii], key, kk) then
                if current_indexes[1] == nil then
                    current_indexes[1] = ii
                end

                current_indexes[2] = ii
            end
        end

        if current_indexes[1] == nil then
            -- No entries found
            break
        else
            entry_index = current_indexes[1]
        end
    end

    return entry_index
end

---@param keys KeyDescription
---@param index number - Index of the key
local function write_keys(keys, index)
    local lines = {}

    if index == #keys then
        return {
            { "\"" .. keys[index].key .. "\": \"\""},
            true
        }
    end

    local insertions = write_keys(keys, index + 1)

    lines[#lines + 1] = "\"" .. keys[index].key .. "\": {"

    for ii=1, #insertions do
        lines[#lines + 1] = insertions[ii]
    end

    lines[#lines + 1] = "}"

    return lines
end

---@param buffer number
---@param insertion_line number
local function add_comma(buffer, insertion_line)
    local BUFFER_SIZE = 5

    -- Find next non-empty character in reverse
    for ii=insertion_line, 0, -BUFFER_SIZE do
        local previous_lines = vim.api.nvim_buf_get_lines(buffer, ii - BUFFER_SIZE, ii, false)

        if #previous_lines == 0 then
            return
        end

        for jj=#previous_lines, 0, -1 do
            local line = previous_lines[jj]

            for char_index=#line, 0, -1 do
                local char = line:sub(char_index, char_index)

                if char ~= " " and char ~= "\t" and char ~= "\n" and char ~= "\r" then
                    if char == "," then
                        return
                    end


                    -- Insert comma at position
                    vim.api.nvim_buf_set_text(buffer, ii - 1, char_index, ii - 1, char_index, {","})
                    return
                end
            end
        end
    end
end

---@param entries Entry[]
---@param keys KeyDescription[]
---@param buffer number
function M:insert_new_key(entries, keys, buffer)
    -- Close current buffer
    vim.cmd [[quit!]]

    local entry_index = find_best_fitting_entry(entries, keys) or 0
    local entry = entries[entry_index]
    local existing_keys_depth = #utils:split_by_char(entry.key, ".") + 1
    local remaining_keys = table.slice(keys, existing_keys_depth, #keys)

    local _writes = write_keys(remaining_keys, 1)
    local writes = {}

    for ii=1, #_writes do
        if _writes[ii] == true then
            -- Unwrap table
            writes[#writes] = writes[#writes][1]
        else
            writes[#writes + 1] = _writes[ii]
        end
    end

    vim.api.nvim_win_set_cursor(0, {entry.position.line_number, entry.position.value_start})
    -- Hacky way to jump to end of object
    vim.cmd [[execute "normal %"]]
    local start_line = vim.api.nvim_win_get_cursor(0)[1] - 1

    -- Add comma to previous line
    add_comma(buffer, start_line)
    --
    -- Insert new lines
    vim.api.nvim_buf_set_lines(buffer, start_line, start_line, false, writes)
    --
    -- -- -- Format lines
    vim.api.nvim_win_set_cursor(0, {start_line, 1})
    vim.cmd('execute "normal =' .. #writes .. 'j"')
    --
    -- -- Jump to the key
    vim.api.nvim_win_set_cursor(0, {start_line + math.ceil(#writes / 2), 0})
    vim.cmd [[execute "normal $a"]] 

    -- vim.schedule(function()
    --     vim.cmd [[%]]
    -- end)

end

return M;