//! Stdin processing for markdown linting

use crate::file_processor;
use colored::*;
use rumdl_lib::config as rumdl_config;
use rumdl_lib::exit_codes::exit;
use rumdl_lib::rule::{Rule, Severity};
use std::io::{self, Read};

/// Process markdown content from stdin.
///
/// `external_config_warning` reports whether a config-file, CLI-flag, or
/// discovery config warning was already seen (the classes decided in
/// `run_check`); combined with inline-comment detection here it drives the
/// `--deny-config-warnings` exit, which this function owns for the stdin path.
pub fn process_stdin(
    rules: &[Box<dyn Rule>],
    args: &crate::CheckArgs,
    config: &rumdl_config::Config,
    external_config_warning: bool,
) {
    use rumdl_lib::output::{OutputFormat, OutputWriter};

    let quiet = args.quiet;
    let silent = args.silent;

    // In check mode, diagnostics go to stderr by default
    // In fix/format modes, fixed content goes to stdout, so diagnostics go to stdout unless --stderr is specified
    let use_stderr = if args.fix_mode != crate::FixMode::Check {
        args.stderr
    } else {
        true
    };
    // Create output writer for linting results
    let output_writer = OutputWriter::new(use_stderr, silent);

    let output_format = match crate::cli_utils::resolve_output_format(args, config) {
        Ok(fmt) => fmt,
        Err(e) => {
            eprintln!("{}: {}", "Error".red().bold(), e);
            exit::tool_error();
        }
    };

    // Read all content from stdin
    let mut content = String::new();
    if let Err(e) = io::stdin().read_to_string(&mut content) {
        if !args.silent {
            eprintln!("Error reading from stdin: {e}");
        }
        exit::violations_found();
    }

    // Detect original line ending before any processing (I/O boundary)
    let original_line_ending = rumdl_lib::utils::detect_line_ending_enum(&content);

    // Normalize to LF for all internal processing
    content = rumdl_lib::utils::normalize_line_ending(&content, rumdl_lib::utils::LineEnding::Lf).into_owned();

    // Detect unknown rule names in inline disable comments. Computed even under
    // --silent (which only suppresses the printed notices) so the flag can still
    // fail the run.
    let inline_config_warning = {
        let mut inline_warnings = rumdl_lib::inline_config::validate_inline_config_rules(&content);
        let active_rules: std::collections::HashSet<String> = rules.iter().map(|r| r.name().to_string()).collect();
        inline_warnings.extend(rumdl_lib::inline_config::validate_inline_enables_against_active_rules(
            &content,
            &active_rules,
        ));
        let had_any = !inline_warnings.is_empty();
        if !silent {
            let display_name = args.stdin_filename.as_deref().unwrap_or("<stdin>");
            for warn in inline_warnings {
                warn.print_warning(display_name);
            }
        }
        had_any
    };

    // A configuration problem is a tooling error (exit 2) that outranks Markdown
    // violations (exit 1). Computed once, checked at every exit path below so
    // fix/format mode cannot bypass it.
    let deny_config = args.deny_config_warnings && (external_config_warning || inline_config_warning);

    // Determine the filename to use for display and context
    let display_filename = args.stdin_filename.as_deref().unwrap_or("<stdin>");

    // Convert stdin-filename to PathBuf for LintContext
    let source_file = args.stdin_filename.as_ref().map(std::path::PathBuf::from);

    // Use per-file flavor if stdin_filename is provided
    let flavor = args
        .stdin_filename
        .as_ref()
        .map(|f| config.get_flavor_for_file(std::path::Path::new(f)))
        .unwrap_or_else(|| config.markdown_flavor());

    // Apply per-file-ignores keyed on the stdin filename, so piping a file's
    // content (as pre-commit hooks and editors do) honors `[per-file-ignores]`
    // exactly like `rumdl check/fmt <file>`. Without this, linting would report
    // rules the file has excluded; the fix coordinator enforces the same
    // exclusion on the fix pass, so check and fix stay consistent.
    let filtered_rules: Vec<Box<dyn Rule>> = match args.stdin_filename.as_deref() {
        Some(name) => rumdl_lib::rules::filter_rules_for_file(rules, config, std::path::Path::new(name)),
        None => rules.to_vec(),
    };
    let effective_rules: &[Box<dyn Rule>] = &filtered_rules;

    // Lint through the same engine as the file path, so inline config
    // overrides, kramdown suppression, inline-disable ranges, and severity
    // overrides behave identically to `rumdl check <file>`.
    let mut all_warnings = match rumdl_lib::lint(
        &content,
        effective_rules,
        args.verbose,
        flavor,
        source_file.clone(),
        Some(config),
    ) {
        Ok(warnings) => warnings,
        Err(e) => {
            if !silent {
                eprintln!("{}: {}", "Error".red().bold(), e);
            }
            exit::tool_error();
        }
    };

    // Sort warnings by line/column
    all_warnings.sort_by(|a, b| {
        if a.line == b.line {
            a.column.cmp(&b.column)
        } else {
            a.line.cmp(&b.line)
        }
    });

    let has_issues = !all_warnings.is_empty();
    let has_warnings = all_warnings
        .iter()
        .any(|w| matches!(w.severity, Severity::Warning | Severity::Error));
    let has_errors = all_warnings.iter().any(|w| w.severity == Severity::Error);

    // Apply fixes if requested
    if args.fix_mode != crate::FixMode::Check {
        if has_issues {
            let mut fixed_content = content.clone();
            let file_path = args.stdin_filename.as_ref().map(std::path::Path::new);
            let _warnings_fixed = file_processor::apply_fixes_coordinated(
                effective_rules,
                &all_warnings,
                &mut fixed_content,
                quiet,
                silent,
                config,
                file_path,
            );

            // Denormalize back to original line ending before output (I/O boundary)
            let output_content =
                rumdl_lib::utils::normalize_line_ending(&fixed_content, original_line_ending).into_owned();

            // Output the fixed content to stdout
            print!("{output_content}");

            // Re-check the fixed content through the same engine to see if
            // any issues remain. Use same per-file flavor as initial lint.
            // The fixed content is already on stdout; an engine error here
            // must not be reported as "0 remaining", so signal a tool error.
            let remaining_warnings = match rumdl_lib::lint(
                &fixed_content,
                effective_rules,
                args.verbose,
                flavor,
                source_file.clone(),
                Some(config),
            ) {
                Ok(warnings) => warnings,
                Err(e) => {
                    if !silent {
                        eprintln!("{}: failed to re-check fixed content: {}", "Error".red().bold(), e);
                    }
                    exit::tool_error();
                }
            };
            let actual_warnings_fixed =
                file_processor::count_actually_fixed_warnings(rules, config, &all_warnings, &remaining_warnings);

            // Diagnostics always go to stderr in fix mode (stdout has fixed content)
            let fix_writer = OutputWriter::new(true, silent);
            if !remaining_warnings.is_empty() {
                // Batch formats: remaining-only warnings
                let batch_file_warnings = vec![(display_filename.to_string(), remaining_warnings.clone())];
                let batch_all_files = vec![display_filename.to_string()];
                if let Some(output) = output_format.format_batch(&batch_file_warnings, &batch_all_files, 0) {
                    fix_writer.writeln(&output).unwrap_or_else(|e| {
                        eprintln!("Error writing output: {e}");
                    });
                } else {
                    match output_format {
                        // Human-readable text formats: all warnings with [fixed] labels
                        OutputFormat::Text | OutputFormat::Full => {
                            let mut output = String::new();
                            for warning in &all_warnings {
                                let rule_name = warning.rule_name.as_deref().unwrap_or("unknown");
                                let was_fixed = file_processor::is_rule_cli_fixable(rules, config, rule_name)
                                    && warning.fix.is_some()
                                    && !remaining_warnings.iter().any(|w| {
                                        w.line == warning.line
                                            && w.column == warning.column
                                            && w.rule_name == warning.rule_name
                                            && w.message == warning.message
                                    });

                                let fix_indicator = if was_fixed {
                                    " [fixed]".green().to_string()
                                } else {
                                    String::new()
                                };

                                use std::fmt::Write;
                                writeln!(
                                    output,
                                    "{}:{}:{}: {} {}{}",
                                    display_filename.blue().underline(),
                                    warning.line.to_string().cyan(),
                                    warning.column.to_string().cyan(),
                                    format!("[{rule_name:5}]").yellow(),
                                    warning.message,
                                    fix_indicator
                                )
                                .ok();
                            }

                            if output.ends_with('\n') {
                                output.pop();
                            }
                            fix_writer.writeln(&output).unwrap_or_else(|e| {
                                eprintln!("Error writing output: {e}");
                            });
                        }
                        // Other streaming formats: use their formatter with remaining-only
                        _ => {
                            let formatter = output_format.create_formatter();
                            let formatted = formatter.format_warnings_with_content(
                                &remaining_warnings,
                                display_filename,
                                &fixed_content,
                            );
                            fix_writer.writeln(&formatted).unwrap_or_else(|e| {
                                eprintln!("Error writing output: {e}");
                            });
                        }
                    }
                }
                if !quiet {
                    fix_writer
                        .writeln(&format!(
                            "\n{} issue(s) fixed, {} issue(s) remaining",
                            actual_warnings_fixed,
                            remaining_warnings.len()
                        ))
                        .ok();
                }
            }

            // Config problem outranks the fix-mode --fail-on exit below (and the
            // Format-mode fall-through), for `check --fix --stdin` and
            // `fmt --stdin` alike.
            if deny_config {
                exit::tool_error();
            }

            if args.fix_mode != crate::FixMode::Format {
                let remaining_has_warnings = remaining_warnings
                    .iter()
                    .any(|w| matches!(w.severity, Severity::Warning | Severity::Error));
                let remaining_has_errors = remaining_warnings.iter().any(|w| w.severity == Severity::Error);
                let should_fail = match args.fail_on_mode {
                    crate::FailOn::Never => false,
                    crate::FailOn::Error => remaining_has_errors,
                    crate::FailOn::Warning => remaining_has_warnings,
                    crate::FailOn::Any => !remaining_warnings.is_empty(),
                };
                if should_fail {
                    exit::violations_found();
                }
            }
        } else {
            print!("{content}");
        }

        // Covers the no-issues sub-branch (which skips the gate above).
        if deny_config {
            exit::tool_error();
        }

        return;
    }

    // Normal check mode (no fix) - output diagnostics.
    // Batch formats emit one document with all warnings; streaming formats
    // emit per-warning lines plus a human-readable summary.
    let batch_file_warnings = vec![(display_filename.to_string(), all_warnings)];
    let batch_all_files = vec![display_filename.to_string()];
    if let Some(output) = output_format.format_batch(&batch_file_warnings, &batch_all_files, 0) {
        output_writer.writeln(&output).unwrap_or_else(|e| {
            eprintln!("Error writing output: {e}");
        });
    } else {
        let all_warnings = &batch_file_warnings[0].1;
        // Use formatter for line-by-line output
        let formatter = output_format.create_formatter();
        if !all_warnings.is_empty() {
            let formatted = formatter.format_warnings_with_content(all_warnings, display_filename, &content);
            output_writer.writeln(&formatted).unwrap_or_else(|e| {
                eprintln!("Error writing output: {e}");
            });
        }

        // Print summary if not quiet
        if !quiet {
            if has_issues {
                output_writer
                    .writeln(&format!(
                        "\nFound {} issue(s) in {}",
                        all_warnings.len(),
                        display_filename
                    ))
                    .ok();
            } else {
                output_writer
                    .writeln(&format!("No issues found in {display_filename}"))
                    .ok();
            }
        }
    }

    // A config problem outranks the check-mode --fail-on exit.
    if deny_config {
        exit::tool_error();
    }

    // Exit with error code based on --fail-on setting
    let should_fail = match args.fail_on_mode {
        crate::FailOn::Never => false,
        crate::FailOn::Error => has_errors,
        crate::FailOn::Warning => has_warnings,
        crate::FailOn::Any => has_issues,
    };
    if should_fail {
        exit::violations_found();
    }
}
