--- JQuote: A Neovim plugin for cycling through quote characters
--- @module jquote
--- @author Author Name
--- @version 1.0.0
--- @license MIT

local M = {}

--- @class JQuoteOptions
--- @field hotkey string The hotkey for toggling quotes (default: "<leader>tq")
--- @field quote_chars string[] List of quote characters to cycle through
local JQuoteOptions = {}

--- Default configuration options
--- @type JQuoteOptions
local DEFAULT_OPTIONS = {
    hotkey = "<leader>tq",
    quote_chars = { "'", '"', "`" },
}

--- Current plugin options
--- @type JQuoteOptions
M.options = vim.deepcopy(DEFAULT_OPTIONS)

--- Plugin metadata
--- @type table
M._version = "1.0.0"
M._name = "jquote"

--- Validates if a character is one of the configured quote characters
--- @param char string The character to validate
--- @return boolean true if the character is a configured quote character, false otherwise
--- @private
local function is_defined_quote_char(char)
    if type(char) ~= "string" or #char ~= 1 then
        return false
    end
    
    for _, quote_char in ipairs(M.options.quote_chars) do
        if char == quote_char then
            return true
        end
    end
    return false
end

--- Locates the quoted string boundaries containing the cursor position
--- @param line string The text line to analyze
--- @param cursor_col number The 0-based cursor column position
--- @return number|nil start_index The 0-based start position of the opening quote
--- @return number|nil end_index The 0-based end position of the closing quote
--- @return string|nil quote_char The quote character used, or nil if not found
--- @private
local function find_quoted_string_at_cursor(line, cursor_col)
    if type(line) ~= "string" or type(cursor_col) ~= "number" or cursor_col < 0 then
        return nil, nil, nil
    end

    --- @type table[] Array of quote position records
    local quote_positions = {}
    
    -- Scan line for quote characters and record their positions
    for i = 1, #line do
        local char = line:sub(i, i)
        if is_defined_quote_char(char) then
            table.insert(quote_positions, { 
                char = char, 
                index = i - 1  -- Convert to 0-based indexing
            })
        end
    end

    -- Find matching quote pairs and check if cursor is within bounds
    for i = 1, #quote_positions do
        local start_quote = quote_positions[i]
        for j = i + 1, #quote_positions do
            local end_quote = quote_positions[j]
            
            -- Match opening and closing quotes of same type
            if start_quote.char == end_quote.char then
                if cursor_col >= start_quote.index and cursor_col <= end_quote.index then
                    return start_quote.index, end_quote.index, start_quote.char
                end
                
                -- Skip to next pair to avoid nested matches
                i = j
                goto continue_outer_loop
            end
        end
        ::continue_outer_loop::
    end

    return nil, nil, nil
end

--- Determines the next quote character in the rotation sequence
--- @param current_char string The current quote character
--- @return string The next quote character in the configured sequence
--- @private
local function get_next_quote_char(current_char)
    if type(current_char) ~= "string" then
        return M.options.quote_chars[1]
    end
    
    local quote_count = #M.options.quote_chars
    
    for i = 1, quote_count do
        if M.options.quote_chars[i] == current_char then
            -- Cycle to next character (wrapping around to first if at end)
            local next_index = (i % quote_count) + 1
            return M.options.quote_chars[next_index]
        end
    end
    
    -- Fallback to first quote character if current not found
    return M.options.quote_chars[1]
end

--- Toggles quote characters around the string at the cursor position
--- Changes quotes in a cyclic manner based on the configured quote_chars sequence
--- @return boolean true if quotes were successfully toggled, false otherwise
function M.toggle_quotes()
    local success, current_line = pcall(vim.api.nvim_get_current_line)
    if not success or type(current_line) ~= "string" then
        vim.notify("JQuote: Failed to get current line", vim.log.levels.ERROR)
        return false
    end
    
    local success_cursor, cursor_pos = pcall(vim.api.nvim_win_get_cursor, 0)
    if not success_cursor or type(cursor_pos) ~= "table" or #cursor_pos < 2 then
        vim.notify("JQuote: Failed to get cursor position", vim.log.levels.ERROR)
        return false
    end
    
    local cursor_row, cursor_col = cursor_pos[1], cursor_pos[2]
    local start_idx, end_idx, current_char = find_quoted_string_at_cursor(current_line, cursor_col)

    if not start_idx or not end_idx or not current_char then
        vim.notify("JQuote: No quoted string found at cursor position", vim.log.levels.INFO)
        return false
    end

    local next_char = get_next_quote_char(current_char)
    if next_char == current_char then
        vim.notify("JQuote: No alternative quote character available", vim.log.levels.WARN)
        return false
    end

    -- Construct new line with replaced quote characters
    local new_line = table.concat({
        current_line:sub(1, start_idx),
        next_char,
        current_line:sub(start_idx + 2, end_idx),
        next_char,
        current_line:sub(end_idx + 2)
    })

    local success_set = pcall(vim.api.nvim_set_current_line, new_line)
    if not success_set then
        vim.notify("JQuote: Failed to update line", vim.log.levels.ERROR)
        return false
    end
    
    -- Restore cursor position
    pcall(vim.api.nvim_win_set_cursor, 0, { cursor_row, cursor_col })
    return true
end

--- Validates user configuration options
--- @param options table The options to validate
--- @return boolean is_valid Whether the options are valid
--- @return string|nil error_message Error message if validation fails
--- @private
local function validate_options(options)
    if type(options) ~= "table" then
        return false, "Options must be a table"
    end
    
    if options.hotkey and type(options.hotkey) ~= "string" then
        return false, "hotkey must be a string"
    end
    
    if options.quote_chars then
        if type(options.quote_chars) ~= "table" then
            return false, "quote_chars must be a table"
        end
        
        if #options.quote_chars == 0 then
            return false, "quote_chars cannot be empty"
        end
        
        for i, char in ipairs(options.quote_chars) do
            if type(char) ~= "string" or #char ~= 1 then
                return false, string.format("quote_chars[%d] must be a single character string", i)
            end
        end
    end
    
    return true, nil
end

--- Initializes the plugin with user-provided configuration
--- @param user_options JQuoteOptions|nil User configuration options
--- @return boolean success Whether setup completed successfully
function M.setup(user_options)
    user_options = user_options or {}
    
    -- Validate user options
    local is_valid, error_msg = validate_options(user_options)
    if not is_valid then
        vim.notify(string.format("JQuote setup error: %s", error_msg), vim.log.levels.ERROR)
        return false
    end
    
    -- Merge with defaults using safe deep extend
    local success, merged_options = pcall(vim.tbl_deep_extend, "force", vim.deepcopy(DEFAULT_OPTIONS), user_options)
    if not success then
        vim.notify("JQuote: Failed to merge configuration options", vim.log.levels.ERROR)
        return false
    end
    
    M.options = merged_options
    
    -- Defensive check for quote_chars integrity
    if not M.options.quote_chars or #M.options.quote_chars == 0 then
        vim.notify("JQuote: quote_chars corrupted, restoring defaults", vim.log.levels.WARN)
        M.options.quote_chars = vim.deepcopy(DEFAULT_OPTIONS.quote_chars)
    end

    -- Configure key mapping with error handling
    local keymap_opts = {
        desc = "JQuote: Toggle quote characters",
        silent = true,
        noremap = true,
    }

    local success_keymap = pcall(vim.keymap.set, "n", M.options.hotkey, M.toggle_quotes, keymap_opts)
    if not success_keymap then
        vim.notify(string.format("JQuote: Failed to set keymap for '%s'", M.options.hotkey), vim.log.levels.ERROR)
        return false
    end
    
    vim.notify(string.format("JQuote: Initialized with hotkey '%s'", M.options.hotkey), vim.log.levels.INFO)
    return true
end

--- Health check function for plugin diagnostics
--- @return table health_info Plugin health information
function M.health()
    local health_info = {
        version = M._version,
        options = M.options,
        quote_chars_count = M.options.quote_chars and #M.options.quote_chars or 0,
        hotkey_configured = M.options.hotkey ~= nil,
    }
    
    return health_info
end

return M