use crate::evaluate::scope::Scope;
use crate::whole_stream_command::WholeStreamCommand;
use indexmap::IndexMap;
use itertools::Itertools;
use nu_protocol::{NamedType, PositionalType, Signature, UntaggedValue, Value};
use nu_source::PrettyDebug;
use std::collections::HashMap;

const COMMANDS_DOCS_DIR: &str = "docs/commands";

#[derive(Default)]
pub struct DocumentationConfig {
    no_subcommands: bool,
    no_color: bool,
    brief: bool,
}

fn generate_doc(name: &str, scope: &Scope) -> IndexMap<String, Value> {
    let mut row_entries = IndexMap::new();
    let command = scope
        .get_command(name)
        .unwrap_or_else(|| panic!("Expected command '{}' from names to be in registry", name));
    row_entries.insert(
        "name".to_owned(),
        UntaggedValue::string(name).into_untagged_value(),
    );
    row_entries.insert(
        "usage".to_owned(),
        UntaggedValue::string(command.usage()).into_untagged_value(),
    );
    retrieve_doc_link(name).and_then(|link| {
        row_entries.insert(
            "doc_link".to_owned(),
            UntaggedValue::string(link).into_untagged_value(),
        )
    });
    row_entries.insert(
        "documentation".to_owned(),
        UntaggedValue::string(get_documentation(
            command.stream_command(),
            scope,
            &DocumentationConfig {
                no_subcommands: true,
                no_color: true,
                brief: false,
            },
        ))
        .into_untagged_value(),
    );
    row_entries
}

// generate_docs gets the documentation from each command and returns a Table as output
pub fn generate_docs(scope: &Scope) -> Value {
    let mut sorted_names = scope.get_command_names();
    sorted_names.sort();

    // cmap will map parent commands to it's subcommands e.g. to -> [to csv, to yaml, to bson]
    let mut cmap: HashMap<String, Vec<String>> = HashMap::new();
    for name in &sorted_names {
        if name.contains(' ') {
            let split_name = name.split_whitespace().collect_vec();
            let parent_name = split_name.first().expect("Expected a parent command name");
            if cmap.contains_key(*parent_name) {
                let sub_names = cmap
                    .get_mut(*parent_name)
                    .expect("Expected an entry for parent");
                sub_names.push(name.to_owned());
            }
        } else {
            cmap.insert(name.to_owned(), Vec::new());
        };
    }
    // Return documentation for each command
    // Sub-commands are nested under their respective parent commands
    let mut table = Vec::new();
    for name in &sorted_names {
        // Must be a sub-command, skip since it's being handled underneath when we hit the parent command
        if !cmap.contains_key(name) {
            continue;
        }
        let mut row_entries = generate_doc(name, scope);
        // Iterate over all the subcommands of the parent command
        let mut sub_table = Vec::new();
        for sub_name in cmap.get(name).unwrap_or(&Vec::new()) {
            let sub_row = generate_doc(sub_name, scope);
            sub_table.push(UntaggedValue::row(sub_row).into_untagged_value());
        }

        if !sub_table.is_empty() {
            row_entries.insert(
                "subcommands".to_owned(),
                UntaggedValue::table(&sub_table).into_untagged_value(),
            );
        }
        table.push(UntaggedValue::row(row_entries).into_untagged_value());
    }
    UntaggedValue::table(&table).into_untagged_value()
}

fn retrieve_doc_link(name: &str) -> Option<String> {
    let doc_name = name.split_whitespace().join("_"); // Because .replace(" ", "_") didn't work
    let mut entries =
        std::fs::read_dir(COMMANDS_DOCS_DIR).expect("Directory for command docs are missing!");
    entries.find_map(|r| {
        r.map_or(None, |de| {
            if de.file_name().to_string_lossy() == format!("{}.{}", &doc_name, "md") {
                Some(format!("/commands/{}.{}", &doc_name, "html"))
            } else {
                None
            }
        })
    })
}

#[allow(clippy::cognitive_complexity)]
pub fn get_documentation(
    cmd: &dyn WholeStreamCommand,
    scope: &Scope,
    config: &DocumentationConfig,
) -> String {
    let cmd_name = cmd.name();
    let signature = cmd.signature();
    let mut long_desc = String::new();

    let usage = &cmd.usage();
    if !usage.is_empty() {
        long_desc.push_str(usage);
        long_desc.push_str("\n\n");
    }

    let extra_usage = if config.brief { "" } else { &cmd.extra_usage() };
    if !extra_usage.is_empty() {
        long_desc.push_str(extra_usage);
        long_desc.push_str("\n\n");
    }

    let mut subcommands = vec![];
    if !config.no_subcommands {
        for name in scope.get_command_names() {
            if name.starts_with(&format!("{} ", cmd_name)) {
                let subcommand = scope.get_command(&name).expect("This shouldn't happen");

                subcommands.push(format!("  {} - {}", name, subcommand.usage()));
            }
        }
    }

    let mut one_liner = String::new();
    one_liner.push_str(&signature.name);
    one_liner.push(' ');

    for positional in &signature.positional {
        match &positional.0 {
            PositionalType::Mandatory(name, _m) => {
                one_liner.push_str(&format!("<{}> ", name));
            }
            PositionalType::Optional(name, _o) => {
                one_liner.push_str(&format!("({}) ", name));
            }
        }
    }

    if signature.rest_positional.is_some() {
        one_liner.push_str("...args ");
    }

    if !subcommands.is_empty() {
        one_liner.push_str("<subcommand> ");
    }

    if !signature.named.is_empty() {
        one_liner.push_str("{flags} ");
    }

    long_desc.push_str(&format!("Usage:\n  > {}\n", one_liner));

    if !subcommands.is_empty() {
        long_desc.push_str("\nSubcommands:\n");
        subcommands.sort();
        long_desc.push_str(&subcommands.join("\n"));
        long_desc.push('\n');
    }

    if !signature.positional.is_empty() || signature.rest_positional.is_some() {
        long_desc.push_str("\nParameters:\n");
        for positional in &signature.positional {
            match &positional.0 {
                PositionalType::Mandatory(name, _m) => {
                    long_desc.push_str(&format!("  <{}> {}\n", name, positional.1));
                }
                PositionalType::Optional(name, _o) => {
                    long_desc.push_str(&format!("  ({}) {}\n", name, positional.1));
                }
            }
        }

        if let Some(rest_positional) = &signature.rest_positional {
            long_desc.push_str(&format!("  ...args: {}\n", rest_positional.2));
        }
    }
    if !signature.named.is_empty() {
        long_desc.push_str(&get_flags_section(&signature))
    }

    let palette = crate::shell::palette::DefaultPalette {};
    let examples = cmd.examples();
    if !examples.is_empty() {
        long_desc.push_str("\nExamples:");
    }
    for example in examples {
        long_desc.push('\n');
        long_desc.push_str("  ");
        long_desc.push_str(example.description);

        if config.no_color {
            long_desc.push_str(&format!("\n  > {}\n", example.example));
        } else {
            let colored_example =
                crate::shell::painter::Painter::paint_string(example.example, scope, &palette);
            long_desc.push_str(&format!("\n  > {}\n", colored_example));
        }
    }

    long_desc.push('\n');

    long_desc
}

fn get_flags_section(signature: &Signature) -> String {
    let mut long_desc = String::new();
    long_desc.push_str("\nFlags:\n");
    for (flag, ty) in &signature.named {
        let msg = match ty.0 {
            NamedType::Switch(s) => {
                if let Some(c) = s {
                    format!(
                        "  -{}, --{}{} {}\n",
                        c,
                        flag,
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                } else {
                    format!(
                        "  --{}{} {}\n",
                        flag,
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                }
            }
            NamedType::Mandatory(s, m) => {
                if let Some(c) = s {
                    format!(
                        "  -{}, --{} <{}> (required parameter){} {}\n",
                        c,
                        flag,
                        m.display(),
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                } else {
                    format!(
                        "  --{} <{}> (required parameter){} {}\n",
                        flag,
                        m.display(),
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                }
            }
            NamedType::Optional(s, o) => {
                if let Some(c) = s {
                    format!(
                        "  -{}, --{} <{}>{} {}\n",
                        c,
                        flag,
                        o.display(),
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                } else {
                    format!(
                        "  --{} <{}>{} {}\n",
                        flag,
                        o.display(),
                        if !ty.1.is_empty() { ":" } else { "" },
                        ty.1
                    )
                }
            }
        };
        long_desc.push_str(&msg);
    }
    long_desc
}

pub fn get_brief_help(cmd: &dyn WholeStreamCommand, scope: &Scope) -> String {
    get_documentation(
        cmd,
        scope,
        &DocumentationConfig {
            no_subcommands: false,
            no_color: false,
            brief: true,
        },
    )
}

pub fn get_full_help(cmd: &dyn WholeStreamCommand, scope: &Scope) -> String {
    get_documentation(cmd, scope, &DocumentationConfig::default())
}