use chrono::NaiveDateTime;
use git2::Commit;
use git2::FileMode;
use git2::ObjectType;
use git2::Oid;
use git2::Repository;
use git2::Tree;
use git2::TreeEntry;
use hyper::header;
use hyper::http::request::Parts;
use serde::Deserialize;
use sputnik::html_escape;
use sputnik::request::SputnikParts;
use std::str::from_utf8;

use crate::action_links;
use crate::controller::Controller;
use crate::diff::diff;
use crate::forms;
use crate::get_renderer;
use crate::ActionParam;
use crate::Context;
use crate::Error;
use crate::HyperResponse;
use crate::Page;
use crate::RenderMode;
use crate::Response;

pub(crate) fn get_blob<C: Controller>(
    entr: TreeEntry,
    params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    match params.action.as_ref() {
        "view" => view_blob(entr, params, controller, ctx, parts),
        "edit" => edit_blob(entr, params, controller, ctx, parts),
        "upload" => Ok(forms::upload_form(true, controller, &ctx, parts).into()),
        "log" => log_blob(entr, params, controller, ctx, parts),
        "diff" => diff_blob(entr, params, controller, ctx, parts),
        "raw" => raw_blob(entr, params, controller, ctx, parts).map(|r| r.into()),
        "run" => run_blob(entr, params, controller, ctx, parts).map(|r| r.into()),
        "move" => move_blob(entr, params, controller, ctx, parts),
        "remove" => remove_blob(params, controller, ctx, parts),
        _ => Err(Error::BadRequest("unknown action".into())),
    }
}

fn view_blob<C: Controller>(
    entr: TreeEntry,
    params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    let mut page = Page {
        title: ctx.path.file_name().unwrap().to_owned(),
        header: action_links(&params.action, controller, &ctx, parts),
        ..Default::default()
    };

    if entr.filemode() == FileMode::Link.into() {
        // TODO: indicate and link symbolic link
    }

    let blob = ctx.repo.find_blob(entr.id()).unwrap();

    if let Some(mime) = mime_guess::from_path(&ctx.path).first() {
        if mime.type_() == "image" {
            page.body
                .push_str("<div class=img-container><img src=?action=raw></div>");
            return Ok(page.into());
        }
    }

    match from_utf8(blob.content()) {
        Ok(text) => {
            if let Some(renderer) = get_renderer(&ctx.path) {
                renderer(text, &mut page, RenderMode::View);
            } else {
                page.body
                    .push_str(&format!("<pre>{}</pre>", html_escape(text)));
            }
        }
        Err(_) => page.body.push_str("failed to decode file as UTF-8"),
    }

    Ok(page.into())
}

fn edit_blob<C: Controller>(
    entr: TreeEntry,
    _params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    if !controller.may_write_path(&ctx, parts) {
        return Err(Error::Unauthorized(
            "you are not authorized to edit this file".into(),
        ));
    }
    let blob = ctx.repo.find_blob(entr.id()).unwrap();
    if let Ok(text) = from_utf8(blob.content()) {
        Ok(forms::edit_text_form(
            &forms::EditForm {
                text: text.to_string(),
                oid: Some(entr.id().to_string()),
                ..Default::default()
            },
            None,
            controller,
            &ctx,
            parts,
        )
        .into())
    } else {
        Ok(forms::upload_form(true, controller, &ctx, parts).into())
    }
}

fn log_blob<C: Controller>(
    _entr: TreeEntry,
    params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    let filename = ctx.path.file_name().unwrap();

    let mut page = Page {
        title: format!("Log for {}", filename),
        header: action_links(&params.action, controller, &ctx, parts),
        ..Default::default()
    };

    let mut walk = ctx.repo.revwalk()?;
    let branch_head = ctx.branch_head()?;
    walk.push(branch_head.id())?;

    let mut prev_commit = branch_head;
    let mut prev_blobid = Some(prev_commit.tree()?.get_path(ctx.path.as_ref())?.id());

    let mut commits = Vec::new();

    // TODO: paginate
    for oid in walk.flatten().skip(1) {
        let commit = ctx.repo.find_commit(oid)?;
        if let Ok(entr) = commit.tree()?.get_path(ctx.path.as_ref()) {
            let blobid = entr.id();
            if Some(blobid) != prev_blobid {
                commits.push(prev_commit);
                prev_blobid = Some(blobid);
            }
            prev_commit = commit;
        } else {
            if prev_blobid.is_some() {
                commits.push(prev_commit);
            }
            prev_commit = commit;
            prev_blobid = None;
        }
    }
    if prev_commit.parent_count() == 0 && prev_commit.tree()?.get_path(ctx.path.as_ref()).is_ok() {
        // the very first commit of the branch
        commits.push(prev_commit);
    }
    page.body.push_str(
        "<form><input type=hidden name=action value=diff>\
        <button>Compare selected revisions</button>",
    );
    let mut prev_date = None;
    for c in commits {
        let date = NaiveDateTime::from_timestamp(c.time().seconds(), 0).date();
        if Some(date) != prev_date {
            if prev_date != None {
                page.body.push_str("</ul>");
            }
            page.body.push_str(&format!(
                "<h2 class=regular-text>{}</h2><ul class=rev-list>",
                date.format("%b %d, %Y")
            ));
        }

        page.body.push_str(&format!(
            "<li>\
            <input type=radio name=oldid required value={0}>\
            <input type=radio name=id required value={0}> ",
            c.id().to_string()
        ));
        page.body.push_str(&format!(
            "<a href='?action=diff&id={}'>{}: {}</a></li>",
            html_escape(c.id().to_string()),
            html_escape(c.author().name().unwrap_or_default()),
            html_escape(c.summary().unwrap_or_default()),
        ));
        prev_date = Some(date);
    }
    page.body.push_str("</ul></form>");
    Ok(page.into())
}

#[derive(Deserialize)]
struct DiffParams {
    id: String,
    oldid: Option<String>,
}

fn find_commit<'a>(repo: &'a Repository, id: &str, branch_head: &Oid) -> Option<Commit<'a>> {
    let oid = Oid::from_str(id).ok()?;
    repo.find_commit(oid)
        .ok()
        // disallow viewing commits from other branches you shouldn't have access to
        .filter(|c| oid == *branch_head || repo.graph_descendant_of(*branch_head, c.id()).unwrap())
}

fn diff_blob<C: Controller>(
    _entr: TreeEntry,
    action_param: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    let params: DiffParams = parts.query()?;
    let branch_commit = ctx.branch_head()?;

    let mut commit = find_commit(&ctx.repo, &params.id, &branch_commit.id())
        .ok_or_else(|| Error::NotFound("commit not found".into()))?;

    let old_commit = if let Some(oldid) = &params.oldid {
        let other_commit = find_commit(&ctx.repo, oldid, &branch_commit.id())
            .ok_or_else(|| Error::NotFound("commit not found".into()))?;

        if other_commit.time() > commit.time() {
            // TODO: redirect instead
            let c = commit;
            commit = other_commit;
            Some(c)
        } else {
            Some(other_commit)
        }
    } else {
        // TODO: what if there are multiple parents?
        commit.parents().next()
    };

    let blob_id = if let Ok(entry) = commit.tree()?.get_path(ctx.path.as_ref()) {
        entry.id()
    } else {
        return Ok(Page {
            title: format!("Commit for {}", ctx.path.file_name().unwrap()),
            body: "file removed".into(),
            header: action_links(&action_param.action, controller, &ctx, parts),
            ..Default::default()
        }
        .into());
    };

    let old_blob_id = old_commit
        .and_then(|p| p.tree().unwrap().get_path(ctx.path.as_ref()).ok())
        .map(|e| e.id());

    if Some(blob_id) == old_blob_id {
        return Err(Error::NotFound("no difference".into()));
    }

    let mut page = Page {
        title: format!(
            "{} for {}",
            if params.oldid.is_some() {
                "Diff"
            } else {
                "Commit"
            },
            ctx.path.file_name().unwrap()
        ),
        header: action_links(&action_param.action, controller, &ctx, parts),
        ..Default::default()
    };
    page.body.push_str("<div>");
    if params.oldid.is_none() {
        page.body.push_str(&format!(
            "<h1>{}</h1>{} committed on {}",
            html_escape(commit.summary().unwrap_or_default()),
            html_escape(commit.author().name().unwrap_or_default()),
            NaiveDateTime::from_timestamp(commit.time().seconds(), 0).format("%b %d, %Y, %H:%M")
        ));
    }

    // TODO: if UTF-8 decoding fails, link ?action=raw&rev=
    if let Some(old_blob_id) = old_blob_id {
        page.body.push_str(&diff(
            from_utf8(ctx.repo.find_blob(old_blob_id)?.content())?,
            from_utf8(ctx.repo.find_blob(blob_id)?.content())?,
        ))
    } else {
        page.body.push_str(&diff(
            "",
            from_utf8(ctx.repo.find_blob(blob_id)?.content())?,
        ));
    }
    page.body.push_str("</div>");
    Ok(page.into())
}

fn build_raw_response(
    entr: TreeEntry,
    ctx: &Context,
    parts: &Parts,
) -> Result<HyperResponse, Error> {
    if let Some(etag) = parts
        .headers
        .get(header::IF_NONE_MATCH)
        .and_then(|v| v.to_str().ok())
    {
        if etag.trim_start_matches("W/").trim_matches('"') == entr.id().to_string() {
            return Err(Error::NotModified);
        }
    }

    let blob = ctx.repo.find_blob(entr.id()).unwrap();
    let mut resp = HyperResponse::new(blob.content().to_owned().into());

    resp.headers_mut()
        .insert(header::ETAG, format!("\"{}\"", entr.id()).parse().unwrap());
    resp.headers_mut()
        .insert(header::CACHE_CONTROL, "no-cache".parse().unwrap());
    Ok(resp)
}

fn raw_blob<C: Controller>(
    entr: TreeEntry,
    _params: ActionParam,
    _controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<HyperResponse, Error> {
    let mut resp = build_raw_response(entr, &ctx, parts)?;
    if let Some(mime) = mime_guess::from_path(&ctx.path).first() {
        if mime.type_() == "text" {
            // workaround for Firefox, which downloads non-plain text subtypes
            // instead of displaying them (https://bugzilla.mozilla.org/1319262)
            resp.headers_mut()
                .insert(header::CONTENT_TYPE, "text/plain".parse().unwrap());
        } else {
            resp.headers_mut()
                .insert(header::CONTENT_TYPE, mime.to_string().parse().unwrap());
        }
    }
    Ok(resp)
}

fn run_blob<C: Controller>(
    entr: TreeEntry,
    _params: ActionParam,
    _controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<HyperResponse, Error> {
    if ctx.path.extension() != Some("html") {
        return Err(Error::BadRequest(
            "run action only available for .html files".into(),
        ));
    }
    let mut resp = build_raw_response(entr, &ctx, parts)?;
    resp.headers_mut()
        .insert(header::CONTENT_TYPE, "text/html".parse().unwrap());
    // We want users to be able to view .html applications of other users
    // without having to worry about the application accessing their private
    // files. So we set the CSP: sandbox header which makes browsers treat
    // the page as a unique origin as per the same-origin policy.
    resp.headers_mut().insert(
        header::CONTENT_SECURITY_POLICY,
        "sandbox allow-scripts;".parse().unwrap(),
    );
    Ok(resp)
}

fn move_blob<C: Controller>(
    _entr: TreeEntry,
    _params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    if !controller.may_move_path(&ctx, parts) {
        return Err(Error::Unauthorized(
            "you are not authorized to move this file".into(),
        ));
    }

    let filename = ctx.path.file_name().unwrap();

    return forms::move_form(
        filename,
        &forms::MoveForm {
            dest: ctx.path.as_str().to_owned(),
            msg: None,
        },
        None,
        controller,
        &ctx,
        parts,
    );
}

fn remove_blob<C: Controller>(
    params: ActionParam,
    controller: &C,
    ctx: Context,
    parts: &Parts,
) -> Result<Response, Error> {
    if !controller.may_move_path(&ctx, parts) {
        return Err(Error::Unauthorized(
            "you are not authorized to remove this file".into(),
        ));
    }

    let filename = ctx.path.file_name().unwrap();

    let page = Page {
        title: format!("Remove {}", filename),
        header: action_links(&params.action, controller, &ctx, parts),
        body: "<form method=post autocomplete=off>\
            <label>Message <input name=msg autofocus></label>\
            <button>Remove</button></form>"
            .into(),
        ..Default::default()
    };

    Ok(page.into())
}

pub fn view_tree<C: Controller>(
    tree: Option<Tree>,
    controller: &C,
    ctx: &Context,
    parts: &Parts,
) -> Result<Response, Error> {
    let mut page = Page {
        title: ctx.path.as_str().to_string(),
        ..Default::default()
    };

    page.body.push_str("<ul>");
    if parts.uri.path() != "/" {
        page.body
            .push_str("<li><a href='..' title='go to parent directory'>../</a></li>");
    }

    if let Some(tree) = &tree {
        let mut entries: Vec<_> = tree.iter().collect();
        entries.sort_by_key(|a| a.kind().unwrap().raw());

        for entry in entries {
            // if the name isn't valid utf8 we skip the entry
            if let Some(name) = entry.name() {
                if entry.kind() == Some(ObjectType::Tree) {
                    page.body.push_str(&format!(
                        "<li><a href='{0}/'>{0}/</a></li>",
                        html_escape(name)
                    ));
                } else {
                    page.body.push_str(&format!(
                        "<li><a href='{0}'>{0}</a></li>",
                        html_escape(name)
                    ));
                }
            }
        }
    }
    page.body.push_str("</ul>");

    controller.before_return_tree_page(&mut page, tree, ctx, parts);

    Ok(page.into())
}