use crate::help::highlight_search_in_table;
use nu_color_config::StyleComputer;
use nu_engine::{scope::ScopeData, CallExt};
use nu_protocol::{
    ast::Call,
    engine::{Command, EngineState, Stack},
    span, AliasId, Category, DeclId, Example, IntoInterruptiblePipelineData, IntoPipelineData,
    PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};

#[derive(Clone)]
pub struct HelpModules;

impl Command for HelpModules {
    fn name(&self) -> &str {
        "help modules"
    }

    fn usage(&self) -> &str {
        "Show help on nushell modules."
    }

    fn extra_usage(&self) -> &str {
        r#"When requesting help for a single module, its commands and aliases will be highlighted if they
are also available in the current scope. Commands/aliases that were imported under a different name
(such as with a prefix after `use some-module`) will be highlighted in parentheses."#
    }

    fn signature(&self) -> Signature {
        Signature::build("help modules")
            .category(Category::Core)
            .rest(
                "rest",
                SyntaxShape::String,
                "the name of module to get help on",
            )
            .named(
                "find",
                SyntaxShape::String,
                "string to find in module names and usage",
                Some('f'),
            )
            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
            .allow_variants_without_examples(true)
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "show all modules",
                example: "help modules",
                result: None,
            },
            Example {
                description: "show help for single module",
                example: "help modules my-module",
                result: None,
            },
            Example {
                description: "search for string in module names and usages",
                example: "help modules --find my-module",
                result: None,
            },
        ]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        _input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        help_modules(engine_state, stack, call)
    }
}

pub fn help_modules(
    engine_state: &EngineState,
    stack: &mut Stack,
    call: &Call,
) -> Result<PipelineData, ShellError> {
    let head = call.head;
    let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
    let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;

    // 🚩The following two-lines are copied from filters/find.rs:
    let style_computer = StyleComputer::from_config(engine_state, stack);
    // Currently, search results all use the same style.
    // Also note that this sample string is passed into user-written code (the closure that may or may not be
    // defined for "string").
    let string_style = style_computer.compute("string", &Value::string("search result", head));

    if let Some(f) = find {
        let all_cmds_vec = build_help_modules(engine_state, stack, head);
        let found_cmds_vec =
            highlight_search_in_table(all_cmds_vec, &f.item, &["name", "usage"], &string_style)?;

        return Ok(found_cmds_vec
            .into_iter()
            .into_pipeline_data(engine_state.ctrlc.clone()));
    }

    if rest.is_empty() {
        let found_cmds_vec = build_help_modules(engine_state, stack, head);

        Ok(found_cmds_vec
            .into_iter()
            .into_pipeline_data(engine_state.ctrlc.clone()))
    } else {
        let mut name = String::new();

        for r in &rest {
            if !name.is_empty() {
                name.push(' ');
            }
            name.push_str(&r.item);
        }

        let module_id = if let Some(id) = engine_state.find_module(name.as_bytes(), &[]) {
            id
        } else {
            return Err(ShellError::ModuleNotFoundAtRuntime(
                name,
                span(&rest.iter().map(|r| r.span).collect::<Vec<Span>>()),
            ));
        };

        let module = engine_state.get_module(module_id);

        let module_usage = engine_state.build_module_usage(module_id);

        // TODO: merge this into documentation.rs at some point
        const G: &str = "\x1b[32m"; // green
        const C: &str = "\x1b[36m"; // cyan
        const CB: &str = "\x1b[1;36m"; // cyan bold
        const RESET: &str = "\x1b[0m"; // reset

        let mut long_desc = String::new();

        if let Some((usage, extra_usage)) = module_usage {
            long_desc.push_str(&usage);
            long_desc.push_str("\n\n");

            if !extra_usage.is_empty() {
                long_desc.push_str(&extra_usage);
                long_desc.push_str("\n\n");
            }
        }

        long_desc.push_str(&format!("{G}Module{RESET}: {C}{name}{RESET}"));
        long_desc.push_str("\n\n");

        if !module.decls.is_empty() || module.main.is_some() {
            let commands: Vec<(Vec<u8>, DeclId)> = engine_state.get_decls_sorted(false).collect();

            let mut module_commands = module.decls();
            module_commands.sort_by(|a, b| a.0.cmp(&b.0));

            let commands_str = module_commands
                .iter()
                .map(|(name_bytes, id)| {
                    let name = String::from_utf8_lossy(name_bytes);
                    if let Some((used_name_bytes, _)) =
                        commands.iter().find(|(_, decl_id)| id == decl_id)
                    {
                        if engine_state.find_decl(name.as_bytes(), &[]).is_some() {
                            format!("{CB}{name}{RESET}")
                        } else {
                            let command_name = String::from_utf8_lossy(used_name_bytes);
                            format!("{name} ({CB}{command_name}{RESET})")
                        }
                    } else {
                        format!("{name}")
                    }
                })
                .collect::<Vec<String>>()
                .join(", ");

            long_desc.push_str(&format!("{G}Exported commands{RESET}:\n  {commands_str}"));
            long_desc.push_str("\n\n");
        }

        if !module.aliases.is_empty() {
            let aliases: Vec<(Vec<u8>, AliasId)> = engine_state.get_aliases_sorted(false).collect();

            let mut module_aliases: Vec<(&[u8], AliasId)> = module
                .aliases
                .iter()
                .map(|(name, id)| (name.as_ref(), *id))
                .collect();
            module_aliases.sort_by(|a, b| a.0.cmp(b.0));

            let aliases_str = module_aliases
                .iter()
                .map(|(name_bytes, id)| {
                    let name = String::from_utf8_lossy(name_bytes);
                    if let Some((used_name_bytes, _)) =
                        aliases.iter().find(|(_, alias_id)| id == alias_id)
                    {
                        if engine_state.find_alias(name.as_bytes(), &[]).is_some() {
                            format!("{CB}{name}{RESET}")
                        } else {
                            let alias_name = String::from_utf8_lossy(used_name_bytes);
                            format!("{name} ({CB}{alias_name}{RESET})")
                        }
                    } else {
                        format!("{name}")
                    }
                })
                .collect::<Vec<String>>()
                .join(", ");

            long_desc.push_str(&format!("{G}Exported aliases{RESET}:\n  {aliases_str}"));
            long_desc.push_str("\n\n");
        }

        if module.env_block.is_some() {
            long_desc.push_str(&format!("This module {C}exports{RESET} environment."));
        } else {
            long_desc.push_str(&format!(
                "This module {C}does not export{RESET} environment."
            ));
        }

        let config = engine_state.get_config();
        if !config.use_ansi_coloring {
            long_desc = nu_utils::strip_ansi_string_likely(long_desc);
        }

        Ok(Value::String {
            val: long_desc,
            span: call.head,
        }
        .into_pipeline_data())
    }
}

fn build_help_modules(engine_state: &EngineState, stack: &Stack, span: Span) -> Vec<Value> {
    let mut scope_data = ScopeData::new(engine_state, stack);
    scope_data.populate_modules();

    scope_data.collect_modules(span)
}

#[cfg(test)]
mod test {
    #[test]
    fn test_examples() {
        use super::HelpModules;
        use crate::test_examples;
        test_examples(HelpModules {})
    }
}