use crate::*;
use syn::ext::IdentExt;
use syn::parse::{Error as ParseError, Parse, ParseStream, Result as ParseResult};
use syn::punctuated::Punctuated;
use syn::spanned::Spanned;
use syn::token::Comma;
use syn::{bracketed, Expr, Ident, LitStr, Token};

pub fn parse(
    f: &syn::Field,
    f_ty: Option<&Ty>,
    has_instruction_api: bool,
) -> ParseResult<(ConstraintGroup, ConstraintGroup)> {
    let mut constraints = ConstraintGroupBuilder::new(f_ty);
    for attr in f.attrs.iter().filter(is_account) {
        for c in attr.parse_args_with(Punctuated::<ConstraintToken, Comma>::parse_terminated)? {
            constraints.add(c)?;
        }
    }
    let account_constraints = constraints.build()?;

    let mut constraints = ConstraintGroupBuilder::new(f_ty);
    for attr in f.attrs.iter().filter(is_instruction) {
        if !has_instruction_api {
            return Err(ParseError::new(
                attr.span(),
                "an instruction api must be declared",
            ));
        }
        for c in attr.parse_args_with(Punctuated::<ConstraintToken, Comma>::parse_terminated)? {
            constraints.add(c)?;
        }
    }
    let instruction_constraints = constraints.build()?;

    Ok((account_constraints, instruction_constraints))
}

pub fn is_account(attr: &&syn::Attribute) -> bool {
    attr.path
        .get_ident()
        .map_or(false, |ident| ident == "account")
}

pub fn is_instruction(attr: &&syn::Attribute) -> bool {
    attr.path
        .get_ident()
        .map_or(false, |ident| ident == "instruction")
}

// Parses a single constraint from a parse stream for `#[account(<STREAM>)]`.
pub fn parse_token(stream: ParseStream) -> ParseResult<ConstraintToken> {
    let is_lit = stream.peek(LitStr);
    if is_lit {
        let lit: LitStr = stream.parse()?;
        let c = ConstraintToken::Literal(Context::new(lit.span(), ConstraintLiteral { lit }));
        return Ok(c);
    }

    let ident = stream.call(Ident::parse_any)?;
    let kw = ident.to_string();

    let c = match kw.as_str() {
        "init" => ConstraintToken::Init(Context::new(ident.span(), ConstraintInit {})),
        "zero" => ConstraintToken::Zeroed(Context::new(ident.span(), ConstraintZeroed {})),
        "mut" => ConstraintToken::Mut(Context::new(ident.span(), ConstraintMut {})),
        "signer" => ConstraintToken::Signer(Context::new(ident.span(), ConstraintSigner {})),
        "executable" => {
            ConstraintToken::Executable(Context::new(ident.span(), ConstraintExecutable {}))
        }
        "mint" => {
            stream.parse::<Token![:]>()?;
            stream.parse::<Token![:]>()?;
            let kw = stream.call(Ident::parse_any)?.to_string();
            stream.parse::<Token![=]>()?;

            let span = ident
                .span()
                .join(stream.span())
                .unwrap_or_else(|| ident.span());

            match kw.as_str() {
                "authority" => ConstraintToken::MintAuthority(Context::new(
                    span,
                    ConstraintMintAuthority {
                        mint_auth: stream.parse()?,
                    },
                )),
                "decimals" => ConstraintToken::MintDecimals(Context::new(
                    span,
                    ConstraintMintDecimals {
                        decimals: stream.parse()?,
                    },
                )),
                _ => return Err(ParseError::new(ident.span(), "Invalid attribute")),
            }
        }
        "token" => {
            stream.parse::<Token![:]>()?;
            stream.parse::<Token![:]>()?;
            let kw = stream.call(Ident::parse_any)?.to_string();
            stream.parse::<Token![=]>()?;

            let span = ident
                .span()
                .join(stream.span())
                .unwrap_or_else(|| ident.span());

            match kw.as_str() {
                "mint" => ConstraintToken::TokenMint(Context::new(
                    span,
                    ConstraintTokenMint {
                        mint: stream.parse()?,
                    },
                )),
                "authority" => ConstraintToken::TokenAuthority(Context::new(
                    span,
                    ConstraintTokenAuthority {
                        auth: stream.parse()?,
                    },
                )),
                _ => return Err(ParseError::new(ident.span(), "Invalid attribute")),
            }
        }
        "bump" => {
            let bump = {
                if stream.peek(Token![=]) {
                    stream.parse::<Token![=]>()?;
                    Some(stream.parse()?)
                } else {
                    None
                }
            };
            ConstraintToken::Bump(Context::new(ident.span(), ConstraintTokenBump { bump }))
        }
        _ => {
            stream.parse::<Token![=]>()?;
            let span = ident
                .span()
                .join(stream.span())
                .unwrap_or_else(|| ident.span());
            match kw.as_str() {
                // Deprecated since 0.11
                "belongs_to" => {
                    return Err(ParseError::new(
                        ident.span(),
                        "belongs_to is deprecated, please use has_one",
                    ))
                }
                "has_one" => ConstraintToken::HasOne(Context::new(
                    span,
                    ConstraintHasOne {
                        join_target: stream.parse()?,
                    },
                )),
                "owner" => ConstraintToken::Owner(Context::new(
                    span,
                    ConstraintOwner {
                        owner_target: stream.parse()?,
                    },
                )),
                "rent_exempt" => ConstraintToken::RentExempt(Context::new(
                    span,
                    match stream.parse::<Ident>()?.to_string().as_str() {
                        "skip" => ConstraintRentExempt::Skip,
                        "enforce" => ConstraintRentExempt::Enforce,
                        _ => {
                            return Err(ParseError::new(
                                span,
                                "rent_exempt must be either skip or enforce",
                            ))
                        }
                    },
                )),
                "state" => ConstraintToken::State(Context::new(
                    span,
                    ConstraintState {
                        program_target: stream.parse()?,
                    },
                )),
                "payer" => ConstraintToken::Payer(Context::new(
                    span,
                    ConstraintPayer {
                        target: stream.parse()?,
                    },
                )),
                "space" => ConstraintToken::Space(Context::new(
                    span,
                    ConstraintSpace {
                        space: stream.parse()?,
                    },
                )),
                "seeds" => {
                    let seeds;
                    let bracket = bracketed!(seeds in stream);
                    ConstraintToken::Seeds(Context::new(
                        span.join(bracket.span).unwrap_or(span),
                        ConstraintSeeds {
                            seeds: seeds.parse_terminated(Expr::parse)?,
                        },
                    ))
                }
                "constraint" => ConstraintToken::Raw(Context::new(
                    span,
                    ConstraintRaw {
                        raw: stream.parse()?,
                    },
                )),
                "close" => ConstraintToken::Close(Context::new(
                    span,
                    ConstraintClose {
                        sol_dest: stream.parse()?,
                    },
                )),
                "address" => ConstraintToken::Address(Context::new(
                    span,
                    ConstraintAddress {
                        address: stream.parse()?,
                    },
                )),
                _ => return Err(ParseError::new(ident.span(), "Invalid attribute")),
            }
        }
    };

    Ok(c)
}

#[derive(Default)]
pub struct ConstraintGroupBuilder<'ty> {
    pub f_ty: Option<&'ty Ty>,
    pub init: Option<Context<ConstraintInit>>,
    pub zeroed: Option<Context<ConstraintZeroed>>,
    pub mutable: Option<Context<ConstraintMut>>,
    pub signer: Option<Context<ConstraintSigner>>,
    pub has_one: Vec<Context<ConstraintHasOne>>,
    pub literal: Vec<Context<ConstraintLiteral>>,
    pub raw: Vec<Context<ConstraintRaw>>,
    pub owner: Option<Context<ConstraintOwner>>,
    pub rent_exempt: Option<Context<ConstraintRentExempt>>,
    pub seeds: Option<Context<ConstraintSeeds>>,
    pub executable: Option<Context<ConstraintExecutable>>,
    pub state: Option<Context<ConstraintState>>,
    pub payer: Option<Context<ConstraintPayer>>,
    pub space: Option<Context<ConstraintSpace>>,
    pub close: Option<Context<ConstraintClose>>,
    pub address: Option<Context<ConstraintAddress>>,
    pub token_mint: Option<Context<ConstraintTokenMint>>,
    pub token_authority: Option<Context<ConstraintTokenAuthority>>,
    pub mint_authority: Option<Context<ConstraintMintAuthority>>,
    pub mint_decimals: Option<Context<ConstraintMintDecimals>>,
    pub bump: Option<Context<ConstraintTokenBump>>,
}

impl<'ty> ConstraintGroupBuilder<'ty> {
    pub fn new(f_ty: Option<&'ty Ty>) -> Self {
        Self {
            f_ty,
            init: None,
            zeroed: None,
            mutable: None,
            signer: None,
            has_one: Vec::new(),
            literal: Vec::new(),
            raw: Vec::new(),
            owner: None,
            rent_exempt: None,
            seeds: None,
            executable: None,
            state: None,
            payer: None,
            space: None,
            close: None,
            address: None,
            token_mint: None,
            token_authority: None,
            mint_authority: None,
            mint_decimals: None,
            bump: None,
        }
    }

    pub fn build(mut self) -> ParseResult<ConstraintGroup> {
        // Init.
        if let Some(i) = &self.init {
            match self.mutable {
                Some(m) => {
                    return Err(ParseError::new(
                        m.span(),
                        "mut cannot be provided with init",
                    ))
                }
                None => self
                    .mutable
                    .replace(Context::new(i.span(), ConstraintMut {})),
            };
            // Rent exempt if not explicitly skipped.
            if self.rent_exempt.is_none() {
                self.rent_exempt
                    .replace(Context::new(i.span(), ConstraintRentExempt::Enforce));
            }
            if self.payer.is_none() {
                return Err(ParseError::new(
                    i.span(),
                    "payer must be provided when initializing an account",
                ));
            }
            // When initializing a non-PDA account, the account being
            // initialized must sign to invoke the system program's create
            // account instruction.
            if self.signer.is_none() && self.seeds.is_none() {
                self.signer
                    .replace(Context::new(i.span(), ConstraintSigner {}));
            }
        }

        // Zero.
        if let Some(z) = &self.zeroed {
            match self.mutable {
                Some(m) => {
                    return Err(ParseError::new(
                        m.span(),
                        "mut cannot be provided with zeroed",
                    ))
                }
                None => self
                    .mutable
                    .replace(Context::new(z.span(), ConstraintMut {})),
            };
            // Rent exempt if not explicitly skipped.
            if self.rent_exempt.is_none() {
                self.rent_exempt
                    .replace(Context::new(z.span(), ConstraintRentExempt::Enforce));
            }
        }

        // Seeds.
        if let Some(i) = &self.seeds {
            if self.init.is_some() && self.payer.is_none() {
                return Err(ParseError::new(
                    i.span(),
                    "payer must be provided when creating a program derived address",
                ));
            }
            if self.bump.is_none() {
                return Err(ParseError::new(
                    i.span(),
                    "bump must be provided with seeds",
                ));
            }
        }

        // Token.
        if let Some(token_mint) = &self.token_mint {
            if self.token_authority.is_none() {
                return Err(ParseError::new(
                    token_mint.span(),
                    "token authority must be provided if token mint is",
                ));
            }

            if self.init.is_none() {
                return Err(ParseError::new(
                    token_mint.span(),
                    "init is required for a pda token",
                ));
            }
        }
        if let Some(token_authority) = &self.token_authority {
            if self.token_mint.is_none() {
                return Err(ParseError::new(
                    token_authority.span(),
                    "token authority must be provided if token mint is",
                ));
            }
        }

        // Mint.
        if let Some(mint_decimals) = &self.mint_decimals {
            if self.mint_authority.is_none() {
                return Err(ParseError::new(
                    mint_decimals.span(),
                    "mint authority must be provided if mint decimals is",
                ));
            }
        }
        if let Some(mint_authority) = &self.mint_authority {
            if self.mint_decimals.is_none() {
                return Err(ParseError::new(
                    mint_authority.span(),
                    "mint decimals must be provided if mint authority is",
                ));
            }
        }

        // SPL Space.
        if self.init.is_some()
            && self.seeds.is_some()
            && self.token_mint.is_some()
            && (self.mint_authority.is_some() || self.token_authority.is_some())
            && self.space.is_some()
        {
            return Err(ParseError::new(
                self.space.as_ref().unwrap().span(),
                "space is not required for initializing an spl account",
            ));
        }

        let ConstraintGroupBuilder {
            f_ty: _,
            init,
            zeroed,
            mutable,
            signer,
            has_one,
            literal,
            raw,
            owner,
            rent_exempt,
            seeds,
            executable,
            state,
            payer,
            space,
            close,
            address,
            token_mint,
            token_authority,
            mint_authority,
            mint_decimals,
            bump,
        } = self;

        // Converts Option<Context<T>> -> Option<T>.
        macro_rules! into_inner {
            ($opt:ident) => {
                $opt.map(|c| c.into_inner())
            };
            ($opt:expr) => {
                $opt.map(|c| c.into_inner())
            };
        }
        // Converts Vec<Context<T>> - Vec<T>.
        macro_rules! into_inner_vec {
            ($opt:ident) => {
                $opt.into_iter().map(|c| c.into_inner()).collect()
            };
        }

        let (owner, pda_owner) = {
            if seeds.is_some() {
                (None, owner.map(|o| o.owner_target.clone()))
            } else {
                (owner, None)
            }
        };

        let seeds = seeds.map(|c| ConstraintSeedsGroup {
            is_init: init.is_some(),
            seeds: c.seeds.clone(),
            bump: into_inner!(bump)
                .map(|b| b.bump)
                .expect("bump must be provided with seeds"),
        });
        Ok(ConstraintGroup {
            init: init.as_ref().map(|_| Ok(ConstraintInitGroup {
                seeds: seeds.clone(),
                payer: into_inner!(payer.clone()).map(|a| a.target),
                space: space.clone().map(|s| s.space.clone()),
                kind: if let Some(tm) = &token_mint {
                    InitKind::Token {
                        mint: tm.clone().into_inner().mint,
                        owner: match &token_authority {
                            Some(a) => a.clone().into_inner().auth,
                            None => return Err(ParseError::new(
                                tm.span(),
                                "authority must be provided to initialize a token program derived address"
                            )),
                        },
                    }
                } else if let Some(d) = &mint_decimals {
                    InitKind::Mint {
                        decimals: d.clone().into_inner().decimals,
                        owner: match &mint_authority {
                            Some(a) => a.clone().into_inner().mint_auth,
                            None => return Err(ParseError::new(
                                d.span(),
                                "authority must be provided to initialize a mint program derived address"
                            ))
                        }
                    }
                } else {
                    InitKind::Program {
                        owner: pda_owner.clone(),
                    }
                },
            })).transpose()?,
            zeroed: into_inner!(zeroed),
            mutable: into_inner!(mutable),
            signer: into_inner!(signer),
            has_one: into_inner_vec!(has_one),
            literal: into_inner_vec!(literal),
            raw: into_inner_vec!(raw),
            owner: into_inner!(owner),
            rent_exempt: into_inner!(rent_exempt),
            executable: into_inner!(executable),
            state: into_inner!(state),
            close: into_inner!(close),
            address: into_inner!(address),
            seeds,
        })
    }

    pub fn add(&mut self, c: ConstraintToken) -> ParseResult<()> {
        match c {
            ConstraintToken::Init(c) => self.add_init(c),
            ConstraintToken::Zeroed(c) => self.add_zeroed(c),
            ConstraintToken::Mut(c) => self.add_mut(c),
            ConstraintToken::Signer(c) => self.add_signer(c),
            ConstraintToken::HasOne(c) => self.add_has_one(c),
            ConstraintToken::Literal(c) => self.add_literal(c),
            ConstraintToken::Raw(c) => self.add_raw(c),
            ConstraintToken::Owner(c) => self.add_owner(c),
            ConstraintToken::RentExempt(c) => self.add_rent_exempt(c),
            ConstraintToken::Seeds(c) => self.add_seeds(c),
            ConstraintToken::Executable(c) => self.add_executable(c),
            ConstraintToken::State(c) => self.add_state(c),
            ConstraintToken::Payer(c) => self.add_payer(c),
            ConstraintToken::Space(c) => self.add_space(c),
            ConstraintToken::Close(c) => self.add_close(c),
            ConstraintToken::Address(c) => self.add_address(c),
            ConstraintToken::TokenAuthority(c) => self.add_token_authority(c),
            ConstraintToken::TokenMint(c) => self.add_token_mint(c),
            ConstraintToken::MintAuthority(c) => self.add_mint_authority(c),
            ConstraintToken::MintDecimals(c) => self.add_mint_decimals(c),
            ConstraintToken::Bump(c) => self.add_bump(c),
        }
    }

    fn add_init(&mut self, c: Context<ConstraintInit>) -> ParseResult<()> {
        if self.init.is_some() {
            return Err(ParseError::new(c.span(), "init already provided"));
        }
        if self.zeroed.is_some() {
            return Err(ParseError::new(c.span(), "zeroed already provided"));
        }
        self.init.replace(c);
        Ok(())
    }

    fn add_zeroed(&mut self, c: Context<ConstraintZeroed>) -> ParseResult<()> {
        if self.zeroed.is_some() {
            return Err(ParseError::new(c.span(), "zeroed already provided"));
        }
        if self.init.is_some() {
            return Err(ParseError::new(c.span(), "init already provided"));
        }
        self.zeroed.replace(c);
        Ok(())
    }

    fn add_close(&mut self, c: Context<ConstraintClose>) -> ParseResult<()> {
        if !matches!(self.f_ty, Some(Ty::ProgramAccount(_)))
            && !matches!(self.f_ty, Some(Ty::Account(_)))
            && !matches!(self.f_ty, Some(Ty::Loader(_)))
        {
            return Err(ParseError::new(
                c.span(),
                "close must be on an Account, ProgramAccount, or Loader",
            ));
        }
        if self.mutable.is_none() {
            return Err(ParseError::new(
                c.span(),
                "mut must be provided before close",
            ));
        }
        if self.close.is_some() {
            return Err(ParseError::new(c.span(), "close already provided"));
        }
        self.close.replace(c);
        Ok(())
    }

    fn add_address(&mut self, c: Context<ConstraintAddress>) -> ParseResult<()> {
        if self.address.is_some() {
            return Err(ParseError::new(c.span(), "address already provided"));
        }
        self.address.replace(c);
        Ok(())
    }

    fn add_token_mint(&mut self, c: Context<ConstraintTokenMint>) -> ParseResult<()> {
        if self.token_mint.is_some() {
            return Err(ParseError::new(c.span(), "token mint already provided"));
        }
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before token",
            ));
        }
        self.token_mint.replace(c);
        Ok(())
    }

    fn add_bump(&mut self, c: Context<ConstraintTokenBump>) -> ParseResult<()> {
        if self.bump.is_some() {
            return Err(ParseError::new(c.span(), "bump already provided"));
        }
        if self.seeds.is_none() {
            return Err(ParseError::new(
                c.span(),
                "seeds must be provided before bump",
            ));
        }
        self.bump.replace(c);
        Ok(())
    }

    fn add_token_authority(&mut self, c: Context<ConstraintTokenAuthority>) -> ParseResult<()> {
        if self.token_authority.is_some() {
            return Err(ParseError::new(
                c.span(),
                "token authority already provided",
            ));
        }
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before token authority",
            ));
        }
        self.token_authority.replace(c);
        Ok(())
    }

    fn add_mint_authority(&mut self, c: Context<ConstraintMintAuthority>) -> ParseResult<()> {
        if self.mint_authority.is_some() {
            return Err(ParseError::new(c.span(), "mint authority already provided"));
        }
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before mint authority",
            ));
        }
        self.mint_authority.replace(c);
        Ok(())
    }

    fn add_mint_decimals(&mut self, c: Context<ConstraintMintDecimals>) -> ParseResult<()> {
        if self.mint_decimals.is_some() {
            return Err(ParseError::new(c.span(), "mint decimals already provided"));
        }
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before mint decimals",
            ));
        }
        self.mint_decimals.replace(c);
        Ok(())
    }

    fn add_mut(&mut self, c: Context<ConstraintMut>) -> ParseResult<()> {
        if self.mutable.is_some() {
            return Err(ParseError::new(c.span(), "mut already provided"));
        }
        self.mutable.replace(c);
        Ok(())
    }

    fn add_signer(&mut self, c: Context<ConstraintSigner>) -> ParseResult<()> {
        if self.signer.is_some() {
            return Err(ParseError::new(c.span(), "signer already provided"));
        }
        self.signer.replace(c);
        Ok(())
    }

    fn add_has_one(&mut self, c: Context<ConstraintHasOne>) -> ParseResult<()> {
        if self
            .has_one
            .iter()
            .filter(|item| item.join_target == c.join_target)
            .count()
            > 0
        {
            return Err(ParseError::new(c.span(), "has_one target already provided"));
        }
        self.has_one.push(c);
        Ok(())
    }

    fn add_literal(&mut self, c: Context<ConstraintLiteral>) -> ParseResult<()> {
        self.literal.push(c);
        Ok(())
    }

    fn add_raw(&mut self, c: Context<ConstraintRaw>) -> ParseResult<()> {
        self.raw.push(c);
        Ok(())
    }

    fn add_owner(&mut self, c: Context<ConstraintOwner>) -> ParseResult<()> {
        if self.owner.is_some() {
            return Err(ParseError::new(c.span(), "owner already provided"));
        }
        self.owner.replace(c);
        Ok(())
    }

    fn add_rent_exempt(&mut self, c: Context<ConstraintRentExempt>) -> ParseResult<()> {
        if self.rent_exempt.is_some() {
            return Err(ParseError::new(c.span(), "rent already provided"));
        }
        self.rent_exempt.replace(c);
        Ok(())
    }

    fn add_seeds(&mut self, c: Context<ConstraintSeeds>) -> ParseResult<()> {
        if self.seeds.is_some() {
            return Err(ParseError::new(c.span(), "seeds already provided"));
        }
        self.seeds.replace(c);
        Ok(())
    }

    fn add_executable(&mut self, c: Context<ConstraintExecutable>) -> ParseResult<()> {
        if self.executable.is_some() {
            return Err(ParseError::new(c.span(), "executable already provided"));
        }
        self.executable.replace(c);
        Ok(())
    }

    fn add_state(&mut self, c: Context<ConstraintState>) -> ParseResult<()> {
        if self.state.is_some() {
            return Err(ParseError::new(c.span(), "state already provided"));
        }
        self.state.replace(c);
        Ok(())
    }

    fn add_payer(&mut self, c: Context<ConstraintPayer>) -> ParseResult<()> {
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before payer",
            ));
        }
        if self.payer.is_some() {
            return Err(ParseError::new(c.span(), "payer already provided"));
        }
        self.payer.replace(c);
        Ok(())
    }

    fn add_space(&mut self, c: Context<ConstraintSpace>) -> ParseResult<()> {
        if self.init.is_none() {
            return Err(ParseError::new(
                c.span(),
                "init must be provided before space",
            ));
        }
        if self.space.is_some() {
            return Err(ParseError::new(c.span(), "space already provided"));
        }
        self.space.replace(c);
        Ok(())
    }
}