#!/usr/bin/env perl

use strict;
use warnings;
use JSON::PP;
use IO::File;
use FindBin;
use lib "$FindBin::Bin/../lib";
use JQ::Lite;

# Show help if no arguments are given
if (!@ARGV) {
    print <<'USAGE';
jq-lite - A lightweight jq-like JSON query tool written in pure Perl

Usage:
  jq-lite [options] '.query' [file.json]

Options:
  -r, --raw-output    Print raw strings instead of JSON-encoded values
  -h, --help          Show this help message

Examples:
  cat users.json | jq-lite '.users[].name'
  jq-lite '.users[] | select(.age > 25)' users.json
  jq-lite -r '.users[] | .name' users.json
  jq-lite '.meta has "version"' config.json
  jq-lite '.items | sort | reverse | first' data.json

Query Syntax:
  .key                Access a key (e.g. .user.name)
  .key?               Optional access (no error if missing)
  .array[]            Traverse all array elements
  .array[n]           Index into array
  |                   Pipe to next operation
  select(condition)   Filter values
  Built-in functions: length, keys, first, last, reverse, sort, unique, has

Tips:
  - Query must start with a dot (e.g. '.users[]')
  - Reads from STDIN if no file is provided
  - Outputs JSON by default; use -r for plain text

Homepage:
  https://metacpan.org/pod/JQ::Lite
USAGE
    exit 0;
}

# Argument parsing
my $raw_output = 0;
my $query;
my $filename;

while (@ARGV) {
    my $arg = shift @ARGV;
    if ($arg eq '--raw-output' || $arg eq '-r') {
        $raw_output = 1;
    }
    elsif ($arg eq '--help' || $arg eq '-h') {
        print <<'USAGE';
jq-lite - A lightweight jq-like JSON query tool written in pure Perl

Usage:
  jq-lite [options] '.query' [file.json]

Options:
  -r, --raw-output    Print raw strings instead of JSON-encoded values
  -h, --help          Show this help message

Examples:
  cat users.json | jq-lite '.users[].name'
  jq-lite '.users[] | select(.age > 25)' users.json
  jq-lite -r '.users[] | .name' users.json
  jq-lite '.meta has "version"' config.json
  jq-lite '.items | sort | reverse | first' data.json

Query Syntax:
  .key                Access a key (e.g. .user.name)
  .key?               Optional access (no error if missing)
  .array[]            Traverse all array elements
  .array[n]           Index into array
  |                   Pipe to next operation
  select(condition)   Filter values
  Built-in functions: length, keys, first, last, reverse, sort, unique, has

Tips:
  - Query must start with a dot (e.g. '.users[]')
  - Reads from STDIN if no file is provided
  - Outputs JSON by default; use -r for plain text

Homepage:
  https://metacpan.org/pod/JQ::Lite
USAGE
        exit 0;
    }
    elsif (!defined $query && $arg =~ /^\./) {
        $query = $arg;
    }
    elsif (!defined $query && !-f $arg) {
        die "Error: Invalid query syntax '$arg'\nUsage: jq-lite [--raw-output|-r] '.query' [file.json]\n";
    }
    elsif (!defined $query) {
        $filename = $arg;
    }
    elsif (!defined $filename) {
        $filename = $arg;
    }
    else {
        die "Usage: jq-lite [--raw-output|-r] '.query' [file.json]\n";
    }
}

# Load JSON from file or STDIN
my $json_text;
if (defined $filename) {
    open my $fh, '<', $filename or die "Cannot open file '$filename': $!\n";
    local $/;
    $json_text = <$fh>;
    close $fh;
}
else {
    local $/;
    $json_text = <STDIN>;
}

# Create JQ::Lite object
my $jq = JQ::Lite->new(raw => $raw_output);

# Output helper
sub print_results {
    my @results = @_;
    my $pp = JSON::PP->new->utf8->canonical->pretty;

    for my $r (@results) {
        if (!defined $r) {
            print "null\n";
        }
        elsif ($raw_output && !ref($r)) {
            print "$r\n";
        }
        else {
            print $pp->encode($r);
        }
    }
}

# Interactive mode
if (!defined $query) {
    system("stty -icanon -echo");

    $SIG{INT} = sub {
        system("stty sane");
        print "\n[EXIT]\n";
        exit 0;
    };

    my $input = '';
    my @last_results;

    # Initial display
    my $ok = eval {
        @last_results = $jq->run_query($json_text, '.');
        1;
    };
    if (!$ok || !@last_results) {
        my $data = eval { JSON::PP->new->decode($json_text) };
        if ($data) {
            @last_results = ($data);
        }
    }

    system("clear");
    print "> $input\n";
    if (@last_results) {
        print_results(@last_results);
    } else {
        print "[INFO] Failed to load initial JSON data.\n";
    }

    print "\nType query (ESC to quit):\n";

    while (1) {
        my $char;
        sysread(STDIN, $char, 1);

        my $ord = ord($char);
        last if $ord == 27;

        if ($ord == 127 || $char eq "\b") {
            chop $input if length($input);
        } else {
            $input .= $char;
        }

        system("clear");
        print "> $input\n";

        my @results;
        my $ok = eval {
            @results = $jq->run_query($json_text, $input);
            1;
        };

        if ($ok && @results) {
            @last_results = @results;
        }

        if (!$ok) {
            print "[INFO] Invalid or partial query. Showing last valid results.\n";
        } elsif (!@results) {
            print "[INFO] Query returned no results. Showing last valid results.\n";
        }

        if (@last_results) {
            eval {
                print_results(@last_results);
                1;
            } or do {
                my $e = $@ || 'Unknown error';
                print "[ERROR] Failed to print: $e\n";
            };
        } else {
            print "[INFO] No previous valid results.\n";
        }
    }

    system("stty sane");
    print "\nGoodbye.\n";
    exit 0;
}

# One-shot mode
my @results = eval { $jq->run_query($json_text, $query) };
if ($@) {
    die "[ERROR] Invalid query: $@\n";
}

if (!@results) {
    warn "[INFO] No results returned for query.\n";
    exit 1;
}

print_results(@results);