--- JQuote: A Neovim plugin for cycling through quote characters
--- @module jquote
--- @author Jan
--- @license MIT

local M = {}

--- Plugin constants
--- @type table
local CONSTANTS = {
    JUMP_BEHAVIORS = {
        AUTO = "auto",
        MANUAL = "manual",
    },
    LOG_LEVELS = vim.log.levels,
    PLUGIN_NAME = "JQuote",
    MIN_QUOTE_CHARS = 1,
    MAX_LINE_LENGTH = 10000, -- Safety limit for line processing
    VERSION_FALLBACK = "unknown",
}

--- @class JQuoteOptions
--- @field hotkey string The hotkey for toggling quotes (default: "<leader>tq")
--- @field quote_chars string[] List of quote characters to cycle through (minimum 1 character required)
--- @field jump_behavior "auto"|"manual" Whether to auto-jump to next pair when not inside quotes (default: "auto")
local JQuoteOptions = {}

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

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

--- Plugin metadata
--- @type table
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)
    -- Input validation with early returns
    if type(char) ~= "string" or #char ~= 1 then
        return false
    end

    -- Defensive programming: ensure quote_chars exists and is valid
    if not M.options.quote_chars or type(M.options.quote_chars) ~= "table" then
        return false
    end

    -- Use explicit loop for better readability and performance
    for _, quote_char in ipairs(M.options.quote_chars) do
        if char == quote_char then
            return true
        end
    end
    return false
end

--- Finds the next quote pair forwards from the current 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_next_quote_pair_forward(line, cursor_col)
    -- Comprehensive input validation
    if type(line) ~= "string" or type(cursor_col) ~= "number" or cursor_col < 0 then
        return nil, nil, nil
    end

    -- Safety check for excessively long lines
    if #line > CONSTANTS.MAX_LINE_LENGTH then
        return nil, nil, nil
    end

    --- @type table[] Array of quote position records
    local quote_positions = {}

    -- Scan line for quote characters starting from cursor position
    -- Use math.min to prevent out-of-bounds access
    local start_pos = math.min(cursor_col + 2, #line)
    for i = start_pos, #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 the first matching quote pair using optimized algorithm
    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
                return start_quote.index, end_quote.index, start_quote.char
            end
        end
    end

    return nil, nil, nil
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)
    -- Comprehensive input validation
    if type(line) ~= "string" or type(cursor_col) ~= "number" or cursor_col < 0 then
        return nil, nil, nil
    end

    -- Safety check for excessively long lines
    if #line > CONSTANTS.MAX_LINE_LENGTH 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
                -- Improved cursor boundary check logic
                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

--- Utility function for logging with consistent formatting
--- @param message string The message to log
--- @param level number The log level (from vim.log.levels)
--- @private
local function log_message(message, level)
    if type(message) ~= "string" then
        message = tostring(message)
    end
    local formatted_message = string.format("%s: %s", CONSTANTS.PLUGIN_NAME, message)
    vim.notify(formatted_message, level or CONSTANTS.LOG_LEVELS.INFO)
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)
    -- Input validation with defensive programming
    if type(current_char) ~= "string" then
        log_message("Invalid current_char type, using fallback", CONSTANTS.LOG_LEVELS.WARN)
        return M.options.quote_chars[1] or "'"
    end

    -- Ensure quote_chars is valid
    if not M.options.quote_chars or type(M.options.quote_chars) ~= "table" or #M.options.quote_chars == 0 then
        log_message("Invalid quote_chars configuration, using fallback", CONSTANTS.LOG_LEVELS.ERROR)
        return "'"
    end

    local quote_count = #M.options.quote_chars

    -- Optimized search with explicit bounds checking
    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
    log_message("Current quote character not found in configuration, using first available", CONSTANTS.LOG_LEVELS.WARN)
    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
--- If cursor is not inside a quote pair, automatically jumps to the next pair forwards
--- @return boolean true if quotes were successfully toggled or cursor moved, false otherwise
function M.toggle_quotes()
    -- Enhanced error handling with detailed logging
    local success, current_line = pcall(vim.api.nvim_get_current_line)
    if not success or type(current_line) ~= "string" then
        log_message("Failed to get current line", CONSTANTS.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
        log_message("Failed to get cursor position", CONSTANTS.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 cursor is not inside a quote pair, handle based on jump behavior setting
    if not start_idx or not end_idx or not current_char then
        if M.options.jump_behavior == CONSTANTS.JUMP_BEHAVIORS.AUTO then
            local next_start_idx, next_end_idx, _ = find_next_quote_pair_forward(current_line, cursor_col)
            
            if next_start_idx and next_end_idx then
                -- Move cursor to the start of the next quote pair
                local success_move = pcall(vim.api.nvim_win_set_cursor, 0, { cursor_row, next_start_idx })
                if success_move then
                    log_message("Jumped to next quote pair", CONSTANTS.LOG_LEVELS.INFO)
                    return true
                else
                    log_message("Failed to move cursor to next quote pair", CONSTANTS.LOG_LEVELS.ERROR)
                    return false
                end
            else
                log_message("No quote pairs found forwards on current line", CONSTANTS.LOG_LEVELS.INFO)
                return false
            end
        else
            log_message("No quoted string found at cursor position", CONSTANTS.LOG_LEVELS.INFO)
            return false
        end
    end

    -- Toggle quotes for current pair
    local next_char = get_next_quote_char(current_char)
    if next_char == current_char then
        log_message("No alternative quote character available", CONSTANTS.LOG_LEVELS.WARN)
        return false
    end

    -- Construct new line with replaced quote characters using safe string operations
    local success_construct, new_line = pcall(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)
    })

    if not success_construct or type(new_line) ~= "string" then
        log_message("Failed to construct new line with updated quotes", CONSTANTS.LOG_LEVELS.ERROR)
        return false
    end

    local success_set = pcall(vim.api.nvim_set_current_line, new_line)
    if not success_set then
        log_message("Failed to update line", CONSTANTS.LOG_LEVELS.ERROR)
        return false
    end

    -- Restore cursor position with error handling
    local success_restore = pcall(vim.api.nvim_win_set_cursor, 0, { cursor_row, cursor_col })
    if not success_restore then
        log_message("Warning: Failed to restore cursor position", CONSTANTS.LOG_LEVELS.WARN)
    end

    log_message("Quote characters toggled successfully", CONSTANTS.LOG_LEVELS.INFO)
    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 < CONSTANTS.MIN_QUOTE_CHARS then
            return false, string.format("quote_chars must contain at least %d character(s)", CONSTANTS.MIN_QUOTE_CHARS)
        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

    if options.jump_behavior then
        if type(options.jump_behavior) ~= "string" then
            return false, "jump_behavior must be a string"
        end

        if options.jump_behavior ~= CONSTANTS.JUMP_BEHAVIORS.AUTO and options.jump_behavior ~= CONSTANTS.JUMP_BEHAVIORS.MANUAL then
            return false, "jump_behavior must be either 'auto' or 'manual'"
        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 with enhanced error reporting
    local is_valid, error_msg = validate_options(user_options)
    if not is_valid then
        log_message(string.format("Setup error: %s", error_msg), CONSTANTS.LOG_LEVELS.ERROR)
        return false
    end

    -- Merge with defaults using safe deep extend with enhanced error handling
    local success, merged_options = pcall(vim.tbl_deep_extend, "force", vim.deepcopy(DEFAULT_OPTIONS), user_options)
    if not success then
        log_message("Failed to merge configuration options", CONSTANTS.LOG_LEVELS.ERROR)
        return false
    end

    M.options = merged_options

    -- Enhanced defensive check for quote_chars integrity
    if not M.options.quote_chars or type(M.options.quote_chars) ~= "table" or #M.options.quote_chars < CONSTANTS.MIN_QUOTE_CHARS then
        log_message("quote_chars corrupted or invalid, restoring defaults", CONSTANTS.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
        log_message(string.format("Failed to set keymap for '%s'", M.options.hotkey), CONSTANTS.LOG_LEVELS.ERROR)
        return false
    end

    log_message(string.format("Initialized with hotkey '%s'", M.options.hotkey), CONSTANTS.LOG_LEVELS.INFO)
    return true
end

--- Gets the plugin version from git tags at runtime
--- @return string version The current plugin version or "unknown" if unavailable
function M.get_version()
    local success, handle = pcall(io.popen, "git describe --tags --abbrev=0 2>/dev/null")
    if not success or not handle then
        return CONSTANTS.VERSION_FALLBACK
    end

    local version = handle:read("*a")
    local close_success = pcall(handle.close, handle)
    
    if not close_success then
        log_message("Warning: Failed to close git command handle", CONSTANTS.LOG_LEVELS.WARN)
    end

    if version and type(version) == "string" and #version > 0 then
        -- Remove trailing whitespace and newlines
        version = version:gsub("%s+$", "")
        -- Remove 'v' prefix if present (e.g., v1.0.0 -> 1.0.0)
        if version:match("^v%d") then
            version = version:sub(2)
        end
        -- Additional validation for semantic versioning format
        if version:match("^%d+%.%d+%.%d+") then
            return version
        end
    end

    return CONSTANTS.VERSION_FALLBACK
end

--- Health check function for plugin diagnostics
--- @return table health_info Plugin health information
function M.health()
    local health_info = {
        options = M.options,
        quote_chars_count = M.options.quote_chars and #M.options.quote_chars or 0,
        hotkey_configured = M.options.hotkey ~= nil,
        jump_behavior_valid = M.options.jump_behavior == CONSTANTS.JUMP_BEHAVIORS.AUTO or M.options.jump_behavior == CONSTANTS.JUMP_BEHAVIORS.MANUAL,
        plugin_version = M.get_version(),
    }

    return health_info
end

return M