<?php

namespace JmesPath;

/**
 * Tree visitor used to compile JMESPath expressions into native PHP code.
 */
class TreeCompiler
{
    private $indentation;
    private $source;
    private $vars;
    /**
     * @param array  $ast    AST to compile.
     * @param string $fnName The name of the function to generate.
     * @param string $expr   Expression being compiled.
     *
     * @return string
     */
    public function visit(array $ast, $fnName, $expr)
    {
        $this->vars = [];
        $this->source = $this->indentation = '';
        $this->write("<?php\n")->write('use JmesPath\\TreeInterpreter as Ti;')->write('use JmesPath\\FnDispatcher as Fd;')->write('use JmesPath\\Utils;')->write('')->write('function %s(Ti $interpreter, $value) {', $fnName)->indent()->dispatch($ast)->write('')->write('return $value;')->outdent()->write('}');
        return $this->source;
    }
    /**
     * @param array $node
     * @return mixed
     */
    private function dispatch(array $node)
    {
        return $this->{"visit_{$node['type']}"}($node);
    }
    /**
     * Creates a monotonically incrementing unique variable name by prefix.
     *
     * @param string $prefix Variable name prefix
     *
     * @return string
     */
    private function makeVar($prefix)
    {
        if (!isset($this->vars[$prefix])) {
            $this->vars[$prefix] = 0;
            return '$' . $prefix;
        }
        return '$' . $prefix . ++$this->vars[$prefix];
    }
    /**
     * Writes the given line of source code. Pass positional arguments to write
     * that match the format of sprintf.
     *
     * @param string $str String to write
     * @return $this
     */
    private function write($str)
    {
        $this->source .= $this->indentation;
        if (\func_num_args() == 1) {
            $this->source .= $str . "\n";
            return $this;
        }
        $this->source .= \vsprintf($str, \array_slice(\func_get_args(), 1)) . "\n";
        return $this;
    }
    /**
     * Decreases the indentation level of code being written
     * @return $this
     */
    private function outdent()
    {
        $this->indentation = \substr($this->indentation, 0, -4);
        return $this;
    }
    /**
     * Increases the indentation level of code being written
     * @return $this
     */
    private function indent()
    {
        $this->indentation .= '    ';
        return $this;
    }
    private function visit_or(array $node)
    {
        $a = $this->makeVar('beforeOr');
        return $this->write('%s = $value;', $a)->dispatch($node['children'][0])->write('if (!$value && $value !== "0" && $value !== 0) {')->indent()->write('$value = %s;', $a)->dispatch($node['children'][1])->outdent()->write('}');
    }
    private function visit_and(array $node)
    {
        $a = $this->makeVar('beforeAnd');
        return $this->write('%s = $value;', $a)->dispatch($node['children'][0])->write('if ($value || $value === "0" || $value === 0) {')->indent()->write('$value = %s;', $a)->dispatch($node['children'][1])->outdent()->write('}');
    }
    private function visit_not(array $node)
    {
        return $this->write('// Visiting not node')->dispatch($node['children'][0])->write('// Applying boolean not to result of not node')->write('$value = !Utils::isTruthy($value);');
    }
    private function visit_subexpression(array $node)
    {
        return $this->dispatch($node['children'][0])->write('if ($value !== null) {')->indent()->dispatch($node['children'][1])->outdent()->write('}');
    }
    private function visit_field(array $node)
    {
        $arr = '$value[' . \var_export($node['value'], \true) . ']';
        $obj = '$value->{' . \var_export($node['value'], \true) . '}';
        $this->write('if (is_array($value) || $value instanceof \\ArrayAccess) {')->indent()->write('$value = isset(%s) ? %s : null;', $arr, $arr)->outdent()->write('} elseif ($value instanceof \\stdClass) {')->indent()->write('$value = isset(%s) ? %s : null;', $obj, $obj)->outdent()->write("} else {")->indent()->write('$value = null;')->outdent()->write("}");
        return $this;
    }
    private function visit_index(array $node)
    {
        if ($node['value'] >= 0) {
            $check = '$value[' . $node['value'] . ']';
            return $this->write('$value = (is_array($value) || $value instanceof \\ArrayAccess)' . ' && isset(%s) ? %s : null;', $check, $check);
        }
        $a = $this->makeVar('count');
        return $this->write('if (is_array($value) || ($value instanceof \\ArrayAccess && $value instanceof \\Countable)) {')->indent()->write('%s = count($value) + %s;', $a, $node['value'])->write('$value = isset($value[%s]) ? $value[%s] : null;', $a, $a)->outdent()->write('} else {')->indent()->write('$value = null;')->outdent()->write('}');
    }
    private function visit_literal(array $node)
    {
        return $this->write('$value = %s;', \var_export($node['value'], \true));
    }
    private function visit_pipe(array $node)
    {
        return $this->dispatch($node['children'][0])->dispatch($node['children'][1]);
    }
    private function visit_multi_select_list(array $node)
    {
        return $this->visit_multi_select_hash($node);
    }
    private function visit_multi_select_hash(array $node)
    {
        $listVal = $this->makeVar('list');
        $value = $this->makeVar('prev');
        $this->write('if ($value !== null) {')->indent()->write('%s = [];', $listVal)->write('%s = $value;', $value);
        $first = \true;
        foreach ($node['children'] as $child) {
            if (!$first) {
                $this->write('$value = %s;', $value);
            }
            $first = \false;
            if ($node['type'] == 'multi_select_hash') {
                $this->dispatch($child['children'][0]);
                $key = \var_export($child['value'], \true);
                $this->write('%s[%s] = $value;', $listVal, $key);
            } else {
                $this->dispatch($child);
                $this->write('%s[] = $value;', $listVal);
            }
        }
        return $this->write('$value = %s;', $listVal)->outdent()->write('}');
    }
    private function visit_function(array $node)
    {
        $value = $this->makeVar('val');
        $args = $this->makeVar('args');
        $this->write('%s = $value;', $value)->write('%s = [];', $args);
        foreach ($node['children'] as $arg) {
            $this->dispatch($arg);
            $this->write('%s[] = $value;', $args)->write('$value = %s;', $value);
        }
        return $this->write('$value = Fd::getInstance()->__invoke("%s", %s);', $node['value'], $args);
    }
    private function visit_slice(array $node)
    {
        return $this->write('$value = !is_string($value) && !Utils::isArray($value)')->write('    ? null : Utils::slice($value, %s, %s, %s);', \var_export($node['value'][0], \true), \var_export($node['value'][1], \true), \var_export($node['value'][2], \true));
    }
    private function visit_current(array $node)
    {
        return $this->write('// Visiting current node (no-op)');
    }
    private function visit_expref(array $node)
    {
        $child = \var_export($node['children'][0], \true);
        return $this->write('$value = function ($value) use ($interpreter) {')->indent()->write('return $interpreter->visit(%s, $value);', $child)->outdent()->write('};');
    }
    private function visit_flatten(array $node)
    {
        $this->dispatch($node['children'][0]);
        $merged = $this->makeVar('merged');
        $val = $this->makeVar('val');
        $this->write('// Visiting merge node')->write('if (!Utils::isArray($value)) {')->indent()->write('$value = null;')->outdent()->write('} else {')->indent()->write('%s = [];', $merged)->write('foreach ($value as %s) {', $val)->indent()->write('if (is_array(%s) && isset(%s[0])) {', $val, $val)->indent()->write('%s = array_merge(%s, %s);', $merged, $merged, $val)->outdent()->write('} elseif (%s !== []) {', $val)->indent()->write('%s[] = %s;', $merged, $val)->outdent()->write('}')->outdent()->write('}')->write('$value = %s;', $merged)->outdent()->write('}');
        return $this;
    }
    private function visit_projection(array $node)
    {
        $val = $this->makeVar('val');
        $collected = $this->makeVar('collected');
        $this->write('// Visiting projection node')->dispatch($node['children'][0])->write('');
        if (!isset($node['from'])) {
            $this->write('if (!is_array($value) || !($value instanceof \\stdClass)) { $value = null; }');
        } elseif ($node['from'] == 'object') {
            $this->write('if (!Utils::isObject($value)) { $value = null; }');
        } elseif ($node['from'] == 'array') {
            $this->write('if (!Utils::isArray($value)) { $value = null; }');
        }
        $this->write('if ($value !== null) {')->indent()->write('%s = [];', $collected)->write('foreach ((array) $value as %s) {', $val)->indent()->write('$value = %s;', $val)->dispatch($node['children'][1])->write('if ($value !== null) {')->indent()->write('%s[] = $value;', $collected)->outdent()->write('}')->outdent()->write('}')->write('$value = %s;', $collected)->outdent()->write('}');
        return $this;
    }
    private function visit_condition(array $node)
    {
        $value = $this->makeVar('beforeCondition');
        return $this->write('%s = $value;', $value)->write('// Visiting condition node')->dispatch($node['children'][0])->write('// Checking result of condition node')->write('if (Utils::isTruthy($value)) {')->indent()->write('$value = %s;', $value)->dispatch($node['children'][1])->outdent()->write('} else {')->indent()->write('$value = null;')->outdent()->write('}');
    }
    private function visit_comparator(array $node)
    {
        $value = $this->makeVar('val');
        $a = $this->makeVar('left');
        $b = $this->makeVar('right');
        $this->write('// Visiting comparator node')->write('%s = $value;', $value)->dispatch($node['children'][0])->write('%s = $value;', $a)->write('$value = %s;', $value)->dispatch($node['children'][1])->write('%s = $value;', $b);
        if ($node['value'] == '==') {
            $this->write('$value = Utils::isEqual(%s, %s);', $a, $b);
        } elseif ($node['value'] == '!=') {
            $this->write('$value = !Utils::isEqual(%s, %s);', $a, $b);
        } else {
            $this->write('$value = (is_int(%s) || is_float(%s)) && (is_int(%s) || is_float(%s)) && %s %s %s;', $a, $a, $b, $b, $a, $node['value'], $b);
        }
        return $this;
    }
    /** @internal */
    public function __call($method, $args)
    {
        throw new \RuntimeException(\sprintf('Invalid node encountered: %s', \json_encode($args[0])));
    }
}
