dissolve-python 0.3.0

// Copyright (C) 2024 Jelmer Vernooij <jelmer@samba.org>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Remove deprecated functions decorated with @replace_me from source files.

use anyhow::Result;
use rustpython_ast::{self as ast};
use rustpython_parser::{parse, Mode};
use std::fs;

/// Remove @replace_me decorated functions from source code
///
/// This removes entire functions decorated with @replace_me,
/// not just the decorators. This should only be used after migration is complete
/// and library authors want to clean up their codebase.
///
/// Returns a tuple of (removed_count, resulting_source)
pub fn remove_decorators(
    source: &str,
    before_version: Option<&str>,
    remove_all: bool,
    current_version: Option<&str>,
) -> Result<(usize, String)> {
    if !remove_all && before_version.is_none() && current_version.is_none() {
        // No removal criteria specified, return source unchanged
        return Ok((0, source.to_string()));
    }

    // Parse the source
    let parsed = parse(source, Mode::Module, "<module>")?;

    let mut lines_to_remove = Vec::new();
    let mut removed_count = 0;

    if let ast::Mod::Module(module) = parsed {
        // Check top-level statements
        for (i, stmt) in module.body.iter().enumerate() {
            if should_remove_statement(stmt, before_version, remove_all, current_version) {
                removed_count += 1;
                // Find the line range for this statement
                // In a real implementation, we'd use source positions
                // For now, we'll use a simple approach
                if let Some(line_range) = find_statement_lines(source, i, &module.body) {
                    lines_to_remove.push(line_range);
                }
            }
        }

        // Check methods inside classes (including nested classes)
        for stmt in &module.body {
            let count = collect_removable_statements(
                stmt,
                source,
                before_version,
                remove_all,
                current_version,
                &mut lines_to_remove,
            );
            removed_count += count;
        }
    }

    // Remove the lines
    let mut result_lines = Vec::new();
    let source_lines: Vec<&str> = source.lines().collect();
    let mut skip_until = 0;

    for (i, line) in source_lines.iter().enumerate() {
        if i < skip_until {
            continue;
        }

        let mut should_skip = false;
        for (start, end) in &lines_to_remove {
            if i >= *start && i < *end {
                should_skip = true;
                skip_until = *end;
                break;
            }
        }

        if !should_skip {
            result_lines.push(*line);
        }
    }

    Ok((removed_count, result_lines.join("\n")))
}

/// Recursively collect statements that should be removed, including nested classes
/// Returns the count of removed functions/methods
fn collect_removable_statements(
    stmt: &ast::Stmt,
    source: &str,
    before_version: Option<&str>,
    remove_all: bool,
    current_version: Option<&str>,
    lines_to_remove: &mut Vec<(usize, usize)>,
) -> usize {
    let mut count = 0;
    match stmt {
        ast::Stmt::ClassDef(class) => {
            // Check methods inside this class
            for (i, method) in class.body.iter().enumerate() {
                if should_remove_statement(method, before_version, remove_all, current_version) {
                    count += 1;
                    if let Some(line_range) = find_method_lines(source, class, i) {
                        lines_to_remove.push(line_range);
                    }
                }

                // Recursively check nested classes
                count += collect_removable_statements(
                    method,
                    source,
                    before_version,
                    remove_all,
                    current_version,
                    lines_to_remove,
                );
            }
        }
        _ => {
            // For non-class statements, no need to recurse
        }
    }
    count
}

fn should_remove_statement(
    stmt: &ast::Stmt,
    before_version: Option<&str>,
    remove_all: bool,
    current_version: Option<&str>,
) -> bool {
    match stmt {
        ast::Stmt::FunctionDef(func) => has_replace_me_decorator(
            &func.decorator_list,
            before_version,
            remove_all,
            current_version,
        ),
        ast::Stmt::AsyncFunctionDef(func) => has_replace_me_decorator(
            &func.decorator_list,
            before_version,
            remove_all,
            current_version,
        ),
        ast::Stmt::ClassDef(class) => has_replace_me_decorator(
            &class.decorator_list,
            before_version,
            remove_all,
            current_version,
        ),
        _ => false,
    }
}

fn has_replace_me_decorator(
    decorators: &[ast::Expr],
    before_version: Option<&str>,
    remove_all: bool,
    current_version: Option<&str>,
) -> bool {
    for dec in decorators.iter() {
        match dec {
            ast::Expr::Name(name) if name.id.as_str() == "replace_me" => {
                if remove_all {
                    return true;
                }
            }
            ast::Expr::Call(call) => {
                if let ast::Expr::Name(name) = &*call.func {
                    let func_name = name.id.as_str();
                    if func_name == "replace_me" {
                        if remove_all {
                            return true;
                        }

                        // Check version if specified
                        if let Some(before_ver) = before_version {
                            if let Some(since_ver) = extract_since_version(&call.keywords) {
                                if compare_versions(&since_ver, before_ver) < 0 {
                                    return true;
                                }
                            }
                        }

                        // Check before_version parameter in decorator
                        if let Some(current_ver) = current_version {
                            let decorator_before_ver = extract_before_version(&call.keywords);
                            if let Some(decorator_before_ver) = decorator_before_ver {
                                if compare_versions(current_ver, &decorator_before_ver) >= 0 {
                                    return true;
                                }
                            }
                        }

                        // Check remove_in version
                        if let Some(current_ver) = current_version {
                            if let Some(remove_in_ver) = extract_remove_in_version(&call.keywords) {
                                if compare_versions(current_ver, &remove_in_ver) >= 0 {
                                    return true;
                                }
                            }
                        }
                    }
                }
            }
            _ => {}
        }
    }
    false
}

fn extract_since_version(keywords: &[ast::Keyword]) -> Option<String> {
    for keyword in keywords {
        if let Some(arg) = &keyword.arg {
            if arg.as_str() == "since" {
                if let ast::Expr::Constant(c) = &keyword.value {
                    if let ast::Constant::Str(s) = &c.value {
                        return Some(s.to_string());
                    }
                }
            }
        }
    }
    None
}

fn extract_before_version(keywords: &[ast::Keyword]) -> Option<String> {
    for keyword in keywords {
        if let Some(arg) = &keyword.arg {
            if arg.as_str() == "before_version" {
                if let ast::Expr::Constant(c) = &keyword.value {
                    if let ast::Constant::Str(s) = &c.value {
                        return Some(s.to_string());
                    }
                }
            }
        }
    }
    None
}

fn extract_remove_in_version(keywords: &[ast::Keyword]) -> Option<String> {
    for keyword in keywords {
        if let Some(arg) = &keyword.arg {
            if arg.as_str() == "remove_in" {
                if let ast::Expr::Constant(c) = &keyword.value {
                    if let ast::Constant::Str(s) = &c.value {
                        return Some(s.to_string());
                    }
                }
            }
        }
    }
    None
}

fn compare_versions(v1: &str, v2: &str) -> i32 {
    use crate::core::types::Version;
    match (v1.parse::<Version>(), v2.parse::<Version>()) {
        (Ok(ver1), Ok(ver2)) => match ver1.cmp(&ver2) {
            std::cmp::Ordering::Less => -1,
            std::cmp::Ordering::Equal => 0,
            std::cmp::Ordering::Greater => 1,
        },
        _ => {
            // Fallback to string comparison if parsing fails
            v1.cmp(v2) as i32
        }
    }
}

fn find_statement_lines(
    source: &str,
    stmt_index: usize,
    stmts: &[ast::Stmt],
) -> Option<(usize, usize)> {
    // Simple heuristic: find function/class definitions by name
    let lines: Vec<&str> = source.lines().collect();

    match &stmts[stmt_index] {
        ast::Stmt::FunctionDef(func) => {
            let func_name = &func.name;
            for (i, line) in lines.iter().enumerate() {
                if line.contains(&format!("def {}", func_name)) {
                    // Find the end of the function (next def, class, or dedent)
                    let indent = line.chars().take_while(|c| c.is_whitespace()).count();
                    for (j, end_line) in lines[i + 1..].iter().enumerate() {
                        let end_i = i + j + 1;
                        if !end_line.trim().is_empty() {
                            let end_indent =
                                end_line.chars().take_while(|c| c.is_whitespace()).count();
                            if end_indent <= indent && !end_line.trim_start().starts_with('#') {
                                // Also remove decorators before the function
                                let start = find_decorator_start(&lines, i);
                                return Some((start, end_i));
                            }
                        }
                    }
                    // If we reach the end, include everything
                    let start = find_decorator_start(&lines, i);
                    return Some((start, lines.len()));
                }
            }
        }
        ast::Stmt::ClassDef(class) => {
            let class_name = &class.name;
            for (i, line) in lines.iter().enumerate() {
                if line.contains(&format!("class {}", class_name)) {
                    let indent = line.chars().take_while(|c| c.is_whitespace()).count();
                    for (j, end_line) in lines[i + 1..].iter().enumerate() {
                        let end_i = i + j + 1;
                        if !end_line.trim().is_empty() {
                            let end_indent =
                                end_line.chars().take_while(|c| c.is_whitespace()).count();
                            if end_indent <= indent && !end_line.trim_start().starts_with('#') {
                                let start = find_decorator_start(&lines, i);
                                return Some((start, end_i));
                            }
                        }
                    }
                    let start = find_decorator_start(&lines, i);
                    return Some((start, lines.len()));
                }
            }
        }
        _ => {}
    }

    None
}

fn find_decorator_start(lines: &[&str], def_line: usize) -> usize {
    // Look backwards for decorators
    let mut start = def_line;
    for i in (0..def_line).rev() {
        let line = lines[i].trim();
        if line.starts_with('@') || line.is_empty() || line.starts_with('#') {
            start = i;
        } else {
            break;
        }
    }
    start
}

fn find_method_lines(
    source: &str,
    class: &ast::StmtClassDef,
    method_index: usize,
) -> Option<(usize, usize)> {
    let lines: Vec<&str> = source.lines().collect();

    // Find the class first
    let class_name = &class.name;
    let mut class_line = None;
    for (i, line) in lines.iter().enumerate() {
        if line.contains(&format!("class {}:", class_name)) {
            class_line = Some(i);
            break;
        }
    }

    let class_start = class_line?;

    // Find the method within the class
    match &class.body[method_index] {
        ast::Stmt::FunctionDef(method) => {
            let method_name = &method.name;

            // Look for the method definition starting from after the class line
            for (i, line) in lines[class_start + 1..].iter().enumerate() {
                let actual_i = class_start + 1 + i;
                if line.contains(&format!("def {}", method_name)) {
                    // Find the end of the method (next def, class, or dedent to class level)
                    let class_indent = lines[class_start]
                        .chars()
                        .take_while(|c| c.is_whitespace())
                        .count();
                    let method_indent = line.chars().take_while(|c| c.is_whitespace()).count();

                    for (j, end_line) in lines[actual_i + 1..].iter().enumerate() {
                        let end_i = actual_i + j + 1;
                        if !end_line.trim().is_empty() {
                            let end_indent =
                                end_line.chars().take_while(|c| c.is_whitespace()).count();
                            if end_indent <= method_indent
                                && !end_line.trim_start().starts_with('#')
                            {
                                // Also remove decorators before the method
                                let start = find_decorator_start(&lines, actual_i);
                                return Some((start, end_i));
                            }
                        }
                    }

                    // If we reach the end, include everything to end of class
                    let start = find_decorator_start(&lines, actual_i);

                    // Find end of class
                    for (j, end_line) in lines[actual_i + 1..].iter().enumerate() {
                        let end_i = actual_i + j + 1;
                        if !end_line.trim().is_empty() {
                            let end_indent =
                                end_line.chars().take_while(|c| c.is_whitespace()).count();
                            if end_indent <= class_indent {
                                return Some((start, end_i));
                            }
                        }
                    }

                    return Some((start, lines.len()));
                }
            }
        }
        ast::Stmt::AsyncFunctionDef(method) => {
            let method_name = &method.name;

            // Look for the async method definition
            for (i, line) in lines[class_start + 1..].iter().enumerate() {
                let actual_i = class_start + 1 + i;
                if line.contains(&format!("async def {}", method_name)) {
                    // Similar logic as above for async methods
                    let _class_indent = lines[class_start]
                        .chars()
                        .take_while(|c| c.is_whitespace())
                        .count();
                    let method_indent = line.chars().take_while(|c| c.is_whitespace()).count();

                    for (j, end_line) in lines[actual_i + 1..].iter().enumerate() {
                        let end_i = actual_i + j + 1;
                        if !end_line.trim().is_empty() {
                            let end_indent =
                                end_line.chars().take_while(|c| c.is_whitespace()).count();
                            if end_indent <= method_indent
                                && !end_line.trim_start().starts_with('#')
                            {
                                let start = find_decorator_start(&lines, actual_i);
                                return Some((start, end_i));
                            }
                        }
                    }

                    let start = find_decorator_start(&lines, actual_i);
                    return Some((start, lines.len()));
                }
            }
        }
        _ => {}
    }

    None
}

/// Remove functions decorated with @replace_me from a file
pub fn remove_decorators_from_file(
    file_path: &str,
    before_version: Option<&str>,
    remove_all: bool,
    write: bool,
    current_version: Option<&str>,
) -> Result<(usize, String)> {
    let source = fs::read_to_string(file_path)?;

    let (removed_count, result) =
        remove_decorators(&source, before_version, remove_all, current_version)?;

    if write && result != source {
        fs::write(file_path, &result)?;
    }

    Ok((removed_count, result))
}

/// Remove functions from a file - entry point from main
pub fn remove_from_file(
    file_path: &str,
    before_version: Option<&str>,
    remove_all: bool,
    write: bool,
    current_version: Option<&str>,
) -> Result<(usize, String)> {
    remove_decorators_from_file(
        file_path,
        before_version,
        remove_all,
        write,
        current_version,
    )
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_remove_all() {
        let source = r#"
from dissolve import replace_me

@replace_me()
def old_function():
    return new_function()

def regular_function():
    return 42

@replace_me(since="1.0.0")
def another_old():
    return new_api()
"#;

        let (count, result) = remove_decorators(source, None, true, None).unwrap();
        assert_eq!(count, 2, "Should remove 2 functions");
        assert!(!result.contains("def old_function"));
        assert!(!result.contains("def another_old"));
        assert!(result.contains("def regular_function"));
    }

    #[test]
    fn test_no_removal_criteria() {
        let source = r#"
@replace_me()
def old_function():
    return new_function()
"#;

        let (count, result) = remove_decorators(source, None, false, None).unwrap();
        assert_eq!(count, 0, "Should remove 0 functions");
        assert_eq!(result, source);
    }

    #[test]
    fn test_remove_before_version() {
        let source = r#"
from dissolve import replace_me

@replace_me(since="1.0.0")
def old_v1():
    return new_v1()

@replace_me(since="2.0.0")
def old_v2():
    return new_v2()

def regular_function():
    return 42
"#;

        let (count, result) = remove_decorators(source, Some("1.5.0"), false, None).unwrap();
        assert_eq!(count, 1, "Should remove 1 function");
        // Functions with version < 1.5.0 should be removed
        assert!(!result.contains("def old_v1"));
        // Functions with version >= 1.5.0 should remain
        assert!(result.contains("def old_v2"));
        assert!(result.contains("def regular_function"));
    }
}