use std::sync::Arc;

use crate::config::{self, Config};
use crate::dirs;
use crate::file::display_rel_path;
use crate::task::Task;
use crate::task::task_fetcher::TaskFetcher;
use crate::task::task_list::find_non_executable_task_files;
use crate::ui::table::MiseTable;
use comfy_table::{Attribute, Cell, Row};
use eyre::{Result, bail};
use itertools::Itertools;
use serde_json::json;

/// List available tasks to execute
/// These may be included from the config file or from the project's .mise/tasks directory
/// mise will merge all tasks from all parent directories into this list.
///
/// So if you have global tasks in `~/.config/mise/tasks/*` and project-specific tasks in
/// ~/myproject/.mise/tasks/*, then they'll both be available but the project-specific
/// tasks will override the global ones if they have the same name.
#[derive(Debug, clap::Args)]
#[clap(verbatim_doc_comment, after_long_help = AFTER_LONG_HELP)]
pub struct TasksLs {
    /// Only show global tasks
    #[clap(short, long, overrides_with = "local", verbatim_doc_comment)]
    pub global: bool,

    /// Output in JSON format
    #[clap(short = 'J', long, verbatim_doc_comment)]
    pub json: bool,

    /// Only show non-global tasks
    #[clap(short, long, overrides_with = "global", verbatim_doc_comment)]
    pub local: bool,

    /// Show all columns
    #[clap(short = 'x', long, verbatim_doc_comment)]
    pub extended: bool,

    /// Load all tasks from the entire monorepo, including sibling directories.
    /// By default, only tasks from the current directory hierarchy are loaded.
    #[clap(long, verbatim_doc_comment)]
    pub all: bool,

    /// Display tasks for usage completion
    #[clap(long, hide = true)]
    pub complete: bool,

    /// Show hidden tasks
    #[clap(long, verbatim_doc_comment)]
    pub hidden: bool,

    /// Only show task names, one per line. Useful for piping to fzf and similar tools.
    #[clap(
        long,
        verbatim_doc_comment,
        conflicts_with_all = ["json", "extended", "usage"]
    )]
    pub name_only: bool,

    /// Do not print table header
    #[clap(long, alias = "no-headers", verbatim_doc_comment)]
    pub no_header: bool,

    /// Sort by column. Default is name.
    #[clap(long, value_name = "COLUMN", verbatim_doc_comment)]
    pub sort: Option<SortColumn>,

    /// Sort order. Default is asc.
    #[clap(long, verbatim_doc_comment)]
    pub sort_order: Option<SortOrder>,

    #[clap(long, hide = true)]
    pub usage: bool,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, clap::ValueEnum)]
pub enum SortColumn {
    Name,
    Alias,
    Description,
    Source,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, clap::ValueEnum)]
pub enum SortOrder {
    Asc,
    Desc,
}

impl TasksLs {
    pub fn merge(mut self, later: Self) -> Result<Self> {
        if later.global || later.local {
            self.global = later.global;
            self.local = later.local;
        }
        self.json |= later.json;
        self.extended |= later.extended;
        self.all |= later.all;
        self.complete |= later.complete;
        self.hidden |= later.hidden;
        self.name_only |= later.name_only;
        self.no_header |= later.no_header;
        self.sort = later.sort.or(self.sort);
        self.sort_order = later.sort_order.or(self.sort_order);
        self.usage |= later.usage;
        if self.name_only && (self.json || self.extended || self.usage) {
            bail!("--name-only cannot be used with --json, --extended, or --usage");
        }
        Ok(self)
    }

    pub fn has_options(&self) -> bool {
        self.json || self.has_non_json_options()
    }

    pub fn has_non_json_options(&self) -> bool {
        self.global
            || self.local
            || self.extended
            || self.all
            || self.complete
            || self.hidden
            || self.name_only
            || self.no_header
            || self.sort.is_some()
            || self.sort_order.is_some()
            || self.usage
    }

    pub async fn run(self) -> Result<()> {
        use crate::task::TaskLoadContext;

        let config = Config::get().await?;

        // Create context based on --all flag or when generating completions/usage specs
        // to ensure monorepo tasks (e.g., `//app:task`) are available for autocomplete.
        let ctx = if self.all || self.complete || self.usage {
            Some(TaskLoadContext::all())
        } else {
            None
        };

        let all_tasks = config.tasks_with_context(ctx.as_ref()).await?;

        let tasks = all_tasks
            .values()
            .filter(|t| self.hidden || !t.hide)
            .filter(|t| !self.local || !t.global)
            .filter(|t| !self.global || t.global)
            .cloned()
            .sorted_by(|a, b| self.sort(a, b))
            .collect::<Vec<Task>>();

        // Resolve remote task files before any operation that may need them
        let mut tasks = tasks;
        // always pass no_cache=false as the command doesn't take no-cache argument
        // MISE_TASK_REMOTE_NO_CACHE env var is still respected if set
        TaskFetcher::new(false)
            .fetch_tasks(&config, &mut tasks)
            .await?;

        // Warn about non-executable files only when there are truly no tasks at all
        // (not just filtered out by --hidden/--local/--global)
        if all_tasks.is_empty()
            && !cfg!(windows)
            && let Some(cwd) = &*dirs::CWD
        {
            let includes = config::task_includes_for_dir(cwd, &config.config_files)?;
            if !find_non_executable_task_files(&includes).is_empty() {
                warn!(
                    "no tasks found, but non-executable files exist in task directories.\nFiles must be executable to be detected as tasks. Run `chmod +x` on the task files to fix this."
                );
            }
        }

        if self.complete {
            return self.complete(tasks);
        } else if self.usage {
            self.display_usage(&config, tasks).await?;
        } else if self.json {
            self.display_json(&config, tasks).await?;
        } else if self.name_only {
            self.display_name_only(tasks)?;
        } else {
            self.display(tasks)?;
        }
        Ok(())
    }

    fn display_name_only(&self, tasks: Vec<Task>) -> Result<()> {
        for t in tasks {
            calm_io::stdoutln!("{}", t.display_name)?;
        }
        Ok(())
    }

    fn complete(&self, tasks: Vec<Task>) -> Result<()> {
        for t in tasks {
            let name = t.display_name.replace(":", "\\:");
            let description = t.description.replace(":", "\\:");
            calm_io::stdoutln!("{name}:{description}")?;
        }
        Ok(())
    }

    fn display(&self, tasks: Vec<Task>) -> Result<()> {
        let mut table = MiseTable::new(
            self.no_header,
            if self.extended {
                &["Name", "Aliases", "Source", "Description"]
            } else {
                &["Name", "Description"]
            },
        );
        for task in tasks {
            table.add_row(self.task_to_row(&task));
        }
        table.print()
    }

    async fn display_usage(&self, config: &Arc<Config>, tasks: Vec<Task>) -> Result<()> {
        let mut usage = usage::Spec::default();
        for task in tasks {
            let mut task_spec = task.parse_usage_spec_for_display(config).await?;
            for (name, complete) in task_spec.complete {
                task_spec.cmd.complete.insert(name, complete);
            }
            // Absorb words the caller forwards to the task beyond what it declares, so
            // `mise run <task> -- --not-a-mise-flag` completes instead of erroring with
            // "unexpected word". This must NOT be spelled `-- ARGS_LAST`: jdx/usage#762
            // made an explicit `--` route the positional cursor onto the arg that declared
            // the separator, past earlier args, so a `--`-gated catch-all swallowed the
            // word being completed and `mise run <task> -- <TAB>` offered filenames
            // instead of the task's own choices. A plain trailing variadic takes the
            // overflow without hijacking `--`, and behaves the same on usage 4 and 5.
            task_spec.cmd.args.push(
                usage::SpecArgBuilder::new()
                    .name("ARGS")
                    .help("Arguments to pass to the tasks. Use \":::\" to separate tasks.")
                    .hide(true)
                    .var(true)
                    .build(),
            );
            if let Some(path) = crate::task::extract_monorepo_path(&task.display_name) {
                let prefixed_aliases: Vec<String> = task_spec
                    .cmd
                    .aliases
                    .iter()
                    .map(|a| format!("//{}:{}", path, a))
                    .collect();
                task_spec.cmd.aliases.extend(prefixed_aliases);
            }
            usage
                .cmd
                .subcommands
                .insert(task.display_name.clone(), task_spec.cmd);
        }
        miseprintln!("{}", usage.to_string());
        Ok(())
    }

    async fn display_json(&self, config: &Arc<Config>, tasks: Vec<Task>) -> Result<()> {
        let mut array_items: Vec<serde_json::Value> = Vec::with_capacity(tasks.len());
        for task in tasks {
            // Report the resolved dir (including any inherited task_config.dir)
            // so consumers see the directory the task will actually run in.
            let resolved_dir = task
                .dir(config)
                .await?
                .map(|p| p.to_string_lossy().to_string());
            let env_strs: Vec<String> = task
                .env
                .0
                .iter()
                .chain(task.overlay_env.iter().map(|(d, _)| d))
                .map(|d| d.to_string())
                .collect();
            array_items.push(json!({
                "name": task.display_name,
                "aliases": task.aliases,
                "description": task.description,
                "source": task.config_source,
                "config_sources": task.config_sources(),
                "depends": task.depends,
                "depends_post": task.depends_post,
                "wait_for": task.wait_for,
                "env": env_strs,
                "dir": resolved_dir,
                "hide": task.hide,
                "global": task.global,
                "raw": task.raw,
                "interactive": task.interactive,
                "sources": task.sources,
                "outputs": task.outputs,
                "shell": task.shell,
                "quiet": task.quiet,
                "silent": task.silent,
                "tools": task.tools,
                "usage": task.usage,
                "timeout": task.timeout,
                "run": task.run(),
                "args": task.args,
                "file": task.file,
            }));
        }
        miseprintln!("{}", serde_json::to_string_pretty(&array_items)?);
        Ok(())
    }

    fn sort(&self, a: &Task, b: &Task) -> std::cmp::Ordering {
        let cmp = match self.sort.unwrap_or(SortColumn::Name) {
            SortColumn::Alias => a.aliases.join(", ").cmp(&b.aliases.join(", ")),
            SortColumn::Description => a.description.cmp(&b.description),
            SortColumn::Source => a.config_source.cmp(&b.config_source),
            _ => a.name.cmp(&b.name),
        };

        match self.sort_order.unwrap_or(SortOrder::Asc) {
            SortOrder::Desc => cmp.reverse(),
            _ => cmp,
        }
    }

    fn task_to_row(&self, task: &Task) -> Row {
        let mut row = vec![Cell::new(&task.display_name).add_attribute(Attribute::Bold)];
        if self.extended {
            row.push(Cell::new(task.aliases.join(", ")));
            row.push(Cell::new(
                task.config_sources()
                    .iter()
                    .map(display_rel_path)
                    .join(", "),
            ));
        }
        row.push(Cell::new(&task.description).add_attribute(Attribute::Dim));
        row.into()
    }
}

// TODO: fill this out
static AFTER_LONG_HELP: &str = color_print::cstr!(
    r#"<bold><underline>Examples:</underline></bold>

    $ <bold>mise tasks ls</bold>
"#
);
