use color_eyre::eyre::{Result, eyre};
use ignore::WalkBuilder;
use grep_regex::RegexMatcher;
use grep_searcher::{sinks::UTF8, SearcherBuilder};
use globset::Glob;
use std::path::Path;

pub fn read_file(path: &str) -> Result<String> {
    Ok(std::fs::read_to_string(path)?)
}

pub fn write_file(path: &str, content: &str) -> Result<()> {
    // Create parent directories if they don't exist
    if let Some(parent) = Path::new(path).parent() {
        std::fs::create_dir_all(parent)?;
    }
    std::fs::write(path, content)?;
    Ok(())
}

pub fn edit_file(path: &str, old_string: &str, new_string: &str) -> Result<()> {
    // Read the current file content
    let content = std::fs::read_to_string(path)?;

    // Find all occurrences of old_string
    let matches: Vec<_> = content.match_indices(old_string).collect();

    match matches.len() {
        0 => Err(eyre!("String to replace not found in file: '{}'", old_string)),
        1 => {
            // Exactly one match - safe to replace
            let new_content = content.replace(old_string, new_string);

            // Create a backup before modifying
            let backup_path = format!("{}.backup", path);
            std::fs::write(&backup_path, &content)?;

            // Write the new content
            match std::fs::write(path, new_content) {
                Ok(_) => {
                    // Success - remove backup
                    let _ = std::fs::remove_file(&backup_path);
                    Ok(())
                }
                Err(e) => {
                    // Failed to write - restore from backup
                    let _ = std::fs::rename(&backup_path, path);
                    Err(e.into())
                }
            }
        }
        n => Err(eyre!(
            "Ambiguous replacement: found {} occurrences of '{}' in file. Please make the old_string unique.",
            n,
            old_string
        )),
    }
}

pub fn glob_list(pattern: &str) -> Result<Vec<String>> {
    let glob = Glob::new(pattern)?.compile_matcher();

    // Extract the literal prefix to determine the root directory
    // Find the position of the first glob metacharacter
    let first_glob = pattern
        .find(|c| matches!(c, '*' | '?' | '[' | '{'))
        .unwrap_or(pattern.len());

    // Find the last directory separator before the first glob metacharacter
    let root = if first_glob > 0 {
        let prefix = &pattern[..first_glob];
        prefix.rfind('/').map(|pos| &prefix[..pos]).unwrap_or(".")
    } else {
        "."
    };

    let mut out = Vec::new();
    for result in WalkBuilder::new(root)
        .standard_filters(true)
        .git_ignore(true)
        .git_global(false)
        .git_exclude(false)
        .require_git(false)
        .build()
    {
        let entity = result?;
        if entity.file_type().map(|filetype| filetype.is_file()).unwrap_or(false) {
            if let Some(path) = entity.path().to_str() {
                // Match against the glob pattern
                if glob.is_match(path) {
                    out.push(path.to_string());
                }
            }
        }
    }
    Ok(out)
}

pub fn grep(root: &str, pattern: &str) -> Result<Vec<(String, usize, String)>> {
    let matcher = RegexMatcher::new_line_matcher(pattern)?;
    let mut searcher = SearcherBuilder::new().line_number(true).build();

    let mut results = Vec::new();
    for result in WalkBuilder::new(root)
        .standard_filters(true)
        .git_ignore(true)
        .git_global(false)
        .git_exclude(false)
        .require_git(false)
        .build()
    {
        let entity = result?;
        if !entity.file_type().map(|filetype| filetype.is_file()).unwrap_or(false) { continue; }
        let path = entity.path().to_path_buf();
        let mut line_hits: Vec<(usize, String)> = Vec::new();
        let sink = UTF8(|line_number, line| {
            line_hits.push((line_number as usize, line.to_string()));
            Ok(true)
        });
        let _ = searcher.search_path(&matcher, &path, sink);
        if !line_hits.is_empty() {
            let p = path.to_string_lossy().to_string();
            for (line_number, text) in line_hits {
                results.push((p.clone(), line_number, text));
            }
        }
    }

    Ok(results)
}