package com.moandjiezana.toml;

public class Identifier
{

    static final Identifier INVALID = new Identifier("", null);

    private static final String ALLOWED_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890_-";

    private final String name;
    private final Type type;

    static Identifier from(String name, Context context)
    {
        Type type;
        boolean valid;
        name = name.trim();
        if (name.startsWith("[["))
        {
            type = Type.TABLE_ARRAY;
            valid = isValidTableArray(name, context);
        } else if (name.startsWith("["))
        {
            type = Type.TABLE;
            valid = isValidTable(name, context);
        } else
        {
            type = Type.KEY;
            valid = isValidKey(name, context);
        }

        if (!valid)
        {
            return Identifier.INVALID;
        }

        return new Identifier(extractName(name), type);
    }

    private Identifier(String name, Type type)
    {
        this.name = name;
        this.type = type;
    }

    String getName()
    {
        return name;
    }

    String getBareName()
    {
        if (isKey())
        {
            return name;
        }

        if (isTable())
        {
            return name.substring(1, name.length() - 1);
        }

        return name.substring(2, name.length() - 2);
    }

    boolean isKey()
    {
        return type == Type.KEY;
    }

    boolean isTable()
    {
        return type == Type.TABLE;
    }

    boolean isTableArray()
    {
        return type == Type.TABLE_ARRAY;
    }

    private static enum Type
    {
        KEY, TABLE, TABLE_ARRAY;
    }

    private static String extractName(String raw)
    {
        boolean quoted = false;
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < raw.length(); i++)
        {
            char c = raw.charAt(i);
            if (c == '"' && (i == 0 || raw.charAt(i - 1) != '\\'))
            {
                quoted = !quoted;
                sb.append('"');
            } else if (quoted || !Character.isWhitespace(c))
            {
                sb.append(c);
            }
        }

        return StringValueReaderWriter.STRING_VALUE_READER_WRITER.replaceUnicodeCharacters(sb.toString());
    }

    private static boolean isValidKey(String name, Context context)
    {
        if (name.trim().isEmpty())
        {
            context.errors.invalidKey(name, context.line.get());
            return false;
        }

        boolean quoted = false;
        for (int i = 0; i < name.length(); i++)
        {
            char c = name.charAt(i);

            if (c == '"' && (i == 0 || name.charAt(i - 1) != '\\'))
            {
                if (!quoted && i > 0 && name.charAt(i - 1) != '.')
                {
                    context.errors.invalidKey(name, context.line.get());
                    return false;
                }
                quoted = !quoted;
            } else if (!quoted && (ALLOWED_CHARS.indexOf(c) == -1))
            {
                context.errors.invalidKey(name, context.line.get());
                return false;
            }
        }

        return true;
    }

    private static boolean isValidTable(String name, Context context)
    {
        boolean valid = true;

        if (!name.endsWith("]"))
        {
            valid = false;
        }

        String trimmed = name.substring(1, name.length() - 1).trim();
        if (trimmed.isEmpty() || trimmed.charAt(0) == '.' || trimmed.endsWith("."))
        {
            valid = false;
        }

        if (!valid)
        {
            context.errors.invalidTable(name, context.line.get());
            return false;
        }

        boolean quoted = false;
        boolean dotAllowed = false;
        boolean quoteAllowed = true;
        boolean charAllowed = true;

        for (int i = 0; i < trimmed.length(); i++)
        {
            char c = trimmed.charAt(i);

            if (!valid)
            {
                break;
            }

            if (Keys.isQuote(c))
            {
                if (!quoteAllowed)
                {
                    valid = false;
                } else if (quoted && trimmed.charAt(i - 1) != '\\')
                {
                    charAllowed = false;
                    dotAllowed = true;
                    quoteAllowed = false;
                } else if (!quoted)
                {
                    quoted = true;
                    quoteAllowed = true;
                }
            } else if (quoted)
            {
                continue;
            } else if (c == '.')
            {
                if (dotAllowed)
                {
                    charAllowed = true;
                    dotAllowed = false;
                    quoteAllowed = true;
                } else
                {
                    context.errors.emptyImplicitTable(name, context.line.get());
                    return false;
                }
            } else if (Character.isWhitespace(c))
            {
                char prev = trimmed.charAt(i - 1);
                if (!Character.isWhitespace(prev) && prev != '.')
                {
                    charAllowed = false;
                    dotAllowed = true;
                    quoteAllowed = true;
                }
            } else
            {
                if (charAllowed && ALLOWED_CHARS.indexOf(c) > -1)
                {
                    charAllowed = true;
                    dotAllowed = true;
                    quoteAllowed = false;
                } else
                {
                    valid = false;
                }
            }
        }

        if (!valid)
        {
            context.errors.invalidTable(name, context.line.get());
            return false;
        }

        return true;
    }

    private static boolean isValidTableArray(String line, Context context)
    {
        boolean valid = true;

        if (!line.endsWith("]]"))
        {
            valid = false;
        }

        String trimmed = line.substring(2, line.length() - 2).trim();
        if (trimmed.isEmpty() || trimmed.charAt(0) == '.' || trimmed.endsWith("."))
        {
            valid = false;
        }

        if (!valid)
        {
            context.errors.invalidTableArray(line, context.line.get());
            return false;
        }

        boolean quoted = false;
        boolean dotAllowed = false;
        boolean quoteAllowed = true;
        boolean charAllowed = true;

        for (int i = 0; i < trimmed.length(); i++)
        {
            char c = trimmed.charAt(i);

            if (!valid)
            {
                break;
            }

            if (c == '"')
            {
                if (!quoteAllowed)
                {
                    valid = false;
                } else if (quoted && trimmed.charAt(i - 1) != '\\')
                {
                    charAllowed = false;
                    dotAllowed = true;
                    quoteAllowed = false;
                } else if (!quoted)
                {
                    quoted = true;
                    quoteAllowed = true;
                }
            } else if (quoted)
            {
                continue;
            } else if (c == '.')
            {
                if (dotAllowed)
                {
                    charAllowed = true;
                    dotAllowed = false;
                    quoteAllowed = true;
                } else
                {
                    context.errors.emptyImplicitTable(line, context.line.get());
                    return false;
                }
            } else if (Character.isWhitespace(c))
            {
                char prev = trimmed.charAt(i - 1);
                if (!Character.isWhitespace(prev) && prev != '.' && prev != '"')
                {
                    charAllowed = false;
                    dotAllowed = true;
                    quoteAllowed = true;
                }
            } else
            {
                if (charAllowed && ALLOWED_CHARS.indexOf(c) > -1)
                {
                    charAllowed = true;
                    dotAllowed = true;
                    quoteAllowed = false;
                } else
                {
                    valid = false;
                }
            }
        }

        if (!valid)
        {
            context.errors.invalidTableArray(line, context.line.get());
            return false;
        }

        return true;
    }
}