use std::path::PathBuf;

use just_fmt::kebab_case;
use mingling::{
    Groupped,
    macros::{chain, dispatcher, renderer},
    parser::AsPicker,
};
use serde::Serialize;

use crate::Constants;

const SUGGEST_READ: &str = "Please use `memm read {}` to view the memory again";
const SUGGEST_EXPLORE: &str = "Please use `memm explore` to view available memories";

dispatcher!("remember", CMDRemember => EntryRemember);
dispatcher!("rewrite", CMDRewrite => EntryRewrite);
dispatcher!("forget", CMDForget => EntryForget);
dispatcher!("explore", CMDExplore => EntryExplore);
dispatcher!("read", CMDRead => EntryRead);
dispatcher!("dumpall", CMDDumpAll => EntryDumpAll);

#[chain]
pub fn handle_remember(args: EntryRemember, constants: &Constants) -> Next {
    let (title, content) = args.pick(()).pick::<Vec<String>>(()).unpack();
    remember(constants, title, content.join(" ")).to_render()
}

#[chain]
pub fn handle_rewrite(args: EntryRewrite, constants: &Constants) -> Next {
    let (title, content) = args.pick(()).pick::<Vec<String>>(()).unpack();
    rewrite(constants, title, content.join(" ")).to_render()
}

#[chain]
pub fn handle_forget(args: EntryForget, constants: &Constants) -> Next {
    let title = args.pick(()).unpack();
    forget(constants, title).to_render()
}

#[chain]
pub fn handle_explore(_p: EntryExplore, constants: &Constants) -> Next {
    explore(constants).to_render()
}

#[chain]
pub fn handle_read(args: EntryRead, constants: &Constants) -> Next {
    let title = args.pick(()).unpack();
    read(constants, title).to_render()
}

#[chain]
pub fn handle_dumpall(args: EntryDumpAll, constants: &Constants) -> Next {
    let about = args.pick::<String>("--about").unpack();
    dumpall(constants, about).to_render()
}

#[derive(Serialize, Groupped)]
pub struct ResultExplore {
    pub titles: Vec<String>,
}
#[renderer]
pub fn phantom_render_result_explore(_p: ResultExplore) {}

#[derive(Serialize, Groupped)]
pub struct ResultRead {
    pub exist: bool,
    pub read_success: bool,
    pub content_lines: Vec<String>,
}
#[renderer]
pub fn phantom_render_result_read(_p: ResultRead) {}

#[derive(Serialize, Groupped)]
pub struct ResultWritten {
    pub exist: bool,
    pub write_success: bool,
    pub suggest: String,
}
#[renderer]
pub fn phantom_render_result_written(_p: ResultWritten) {}

#[derive(Serialize, Groupped)]
pub struct ResultForgotten {
    pub exist: bool,
    pub forget_success: bool,
    pub suggest: String,
}
#[renderer]
pub fn phantom_render_result_forgotten(_p: ResultForgotten) {}

#[derive(Serialize, Groupped)]
pub struct ResultDumpAll {
    pub entries: Vec<DumpEntry>,
}

#[derive(Serialize)]
pub struct DumpEntry {
    pub title: String,
    pub content: String,
}

#[renderer]
pub fn phantom_render_result_dumpall(_p: ResultDumpAll) {}

fn explore(constants: &Constants) -> ResultExplore {
    let store_root = &constants.store_root;
    let mut titles = Vec::new();
    if let Ok(entries) = std::fs::read_dir(store_root) {
        for entry in entries.flatten() {
            let path = entry.path();
            if let Some(ext) = path.extension() {
                if ext == "md" {
                    if let Some(stem) = path.file_stem() {
                        titles.push(stem.to_string_lossy().to_string());
                    }
                }
            }
        }
    }
    ResultExplore { titles }
}

fn read(constants: &Constants, title: String) -> ResultRead {
    let target_file = item_path(constants, &title);
    if !target_file.exists() {
        return ResultRead {
            exist: false,
            read_success: false,
            content_lines: Vec::new(),
        };
    }
    match std::fs::read_to_string(&target_file) {
        Ok(content) => ResultRead {
            exist: true,
            read_success: true,
            content_lines: content.lines().map(|line| line.to_string()).collect(),
        },
        Err(_) => ResultRead {
            exist: true,
            read_success: false,
            content_lines: Vec::new(),
        },
    }
}

fn rewrite(constants: &Constants, title: String, content: String) -> ResultWritten {
    let content = content.replace("\\n", "\n");
    let target_file = item_path(constants, &title);
    match std::fs::write(&target_file, content) {
        Ok(_) => ResultWritten {
            exist: true,
            write_success: true,
            suggest: SUGGEST_READ.replace("{}", &title),
        },
        Err(_) => ResultWritten {
            exist: true,
            write_success: false,
            suggest: SUGGEST_READ.replace("{}", &title),
        },
    }
}

fn remember(constants: &Constants, title: String, content: String) -> ResultWritten {
    let content = content.replace("\\n", "\n");
    let target_file = item_path(constants, &title);
    match std::fs::OpenOptions::new()
        .append(true)
        .create(true)
        .open(&target_file)
    {
        Ok(mut file) => {
            use std::io::Write;
            match writeln!(file, "{}", content) {
                Ok(_) => ResultWritten {
                    exist: true,
                    write_success: true,
                    suggest: SUGGEST_READ.replace("{}", &title),
                },
                Err(_) => ResultWritten {
                    exist: true,
                    write_success: false,
                    suggest: SUGGEST_READ.replace("{}", &title),
                },
            }
        }
        Err(_) => ResultWritten {
            exist: false,
            write_success: false,
            suggest: String::new(),
        },
    }
}

fn forget(constants: &Constants, title: String) -> ResultForgotten {
    let target_file = item_path(constants, &title);
    if !target_file.exists() {
        return ResultForgotten {
            exist: false,
            forget_success: false,
            suggest: SUGGEST_EXPLORE.to_string(),
        };
    }
    match std::fs::remove_file(&target_file) {
        Ok(_) => ResultForgotten {
            exist: true,
            forget_success: true,
            suggest: SUGGEST_EXPLORE.to_string(),
        },
        Err(_) => ResultForgotten {
            exist: true,
            forget_success: false,
            suggest: SUGGEST_EXPLORE.to_string(),
        },
    }
}

fn dumpall(constants: &Constants, about: String) -> ResultDumpAll {
    let store_root = &constants.store_root;
    let mut entries = Vec::new();
    if let Ok(dir_entries) = std::fs::read_dir(store_root) {
        for entry in dir_entries.flatten() {
            let path = entry.path();
            if let Some(ext) = path.extension() {
                if ext == "md" {
                    if let Some(stem) = path.file_stem() {
                        let title = stem.to_string_lossy().to_string();
                        let content = std::fs::read_to_string(&path).unwrap_or_default();
                        // If about is provided and not empty, do fuzzy matching on lowercase alphanumeric
                        if !about.is_empty() {
                            let filter: String = about
                                .chars()
                                .filter(|c| c.is_alphanumeric())
                                .collect::<String>()
                                .to_lowercase();
                            let title_clean: String = title
                                .chars()
                                .filter(|c| c.is_alphanumeric())
                                .collect::<String>()
                                .to_lowercase();
                            if !title_clean.contains(&filter) {
                                continue;
                            }
                        }
                        entries.push(DumpEntry { title, content });
                    }
                }
            }
        }
    }
    ResultDumpAll { entries }
}

fn item_path(constants: &Constants, title: &String) -> PathBuf {
    constants
        .store_root
        .join(format!("{}.md", kebab_case!(title)))
}